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DR ANTHONY MELVIN CRASTO, Born in Mumbai in 1964 and graduated from Mumbai University, Completed his Ph.D from ICT, 1991,Matunga, Mumbai, India, in Organic Chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with GLENMARK PHARMACEUTICALS LTD, Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Total Industry exp 29 plus yrs, Prior to joining Glenmark, he has worked with major multinationals like Hoechst Marion Roussel, now Sanofi, Searle India Ltd, now RPG lifesciences, etc. He has worked with notable scientists like Dr K Nagarajan, Dr Ralph Stapel, Prof S Seshadri etc, He did custom synthesis for major multinationals in his career like BASF, Novartis, Sanofi, etc., He has worked in Discovery, Natural products, Bulk drugs, Generics, Intermediates, Fine chemicals, Neutraceuticals, GMP, Scaleups, etc, he is now helping millions, has 9 million plus hits on Google on all Organic chemistry websites. His friends call him worlddrugtracker. His New Drug Approvals, Green Chemistry International, All about drugs, Eurekamoments, Organic spectroscopy international, etc in organic chemistry are some most read blogs He has hands on experience in initiation and developing novel routes for drug molecules and implementation them on commercial scale over a 29 year tenure till date Aug 2016, Around 30 plus products in his career. He has good knowledge of IPM, GMP, Regulatory aspects, he has several International patents published worldwide . He has good proficiency in Technology transfer, Spectroscopy, Stereochemistry, Synthesis, Polymorphism etc., He suffered a paralytic stroke/ Acute Transverse mylitis in Dec 2007 and is 90 %Paralysed, He is bound to a wheelchair, this seems to have injected feul in him to help chemists all around the world, he is more active than before and is pushing boundaries, He has 9 million plus hits on Google, 2.5 lakh plus connections on all networking sites, 25 Lakh plus views on dozen plus blogs, He makes himself available to all, contact him on +91 9323115463, email, Twitter, @amcrasto , He lives and will die for his family, 90% paralysis cannot kill his soul., Notably he has 13 lakh plus views on New Drug Approvals Blog in 212 countries...... , He appreciates the help he gets from one and all, Friends, Family, Glenmark, Readers, Wellwishers, Doctors, Drug authorities, His Contacts, Physiotherapist, etc

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Skeletal formula of triethylenetetramine


  • Molecular Formula C6H18N4
  • Average mass 146.234 Da

112-24-3 CAS

曲恩汀, KD-034, MK-0681, MK-681, TECZA, TETA, TJA-250

1,2-Ethanediamine, N1,N2-bis(2-aminoethyl)-
Image result for TRIENTINE


  • Molecular Formula C6H19ClN4
  • Average mass 182.695 Da

38260-01-4 CAS


Image result for MSD

Image result for VALEANT

Trientine Hydrochloride

C6H18N4▪2HCl : 219.16

Aton Pharma, a subsidiary of Valeant Pharmaceuticals, has developed and launched Syprine, a capsule formulation of trientine hydrochloride, for treating Wilson disease.

Image result for TRIENTINE

Triethylenetetramine, abbreviated TETA and trien and also called trientine (INN), is an organic compound with the formula [CH2NHCH2CH2NH2]2. This oily liquid is colorless but, like many amines, assumes a yellowish color due to impurities resulting from air-oxidation. It is soluble in polar solvents. The branched isomer tris(2-aminoethyl)amine and piperazine derivatives may also be present in commercial samples of TETA.[1]

Trientine hydrochloride is a metal antagonist that was first launched by Merck, Sharp & Dohme in the U.S. in 1986 under the brand name Syprine for the oral treatment of Wilson’s disease.

Orphan drug designation has also been assigned in the U.S. for the treatment of patients with Wilson’s disease who are intolerant or inadequately responsive to penicillamine and in the E.U. by Univar for the treatment of Wilson’s disease

 Trientine hydrochloride pk_prod_list.xml_prod_list_card_pr?p_tsearch=A&p_id=90373

By condensation of ethylenediamine (I) with 1,2-dichloroethane (II)

Trientine hydrochloride is N,N’-bis (2-aminoethyl)-1,2-ethanediamine dihydrochloride. It is a white to pale yellow crystalline hygroscopic powder. It is freely soluble in water, soluble in methanol, slightly soluble in ethanol, and insoluble in chloroform and ether.

The empirical formula is C6H18N4·2HCI with a molecular weight of 219.2. The structural formula is:


Trientine hydrochloride is a chelating compound for removal of excess copper from the body. SYPRINE (Trientine Hydrochloride) is available as 250 mg capsules for oral administration. Capsules SYPRINE contain gelatin, iron oxides, stearic acid, and titanium dioxide as inactive ingredients.

Image result for TRIENTINE


TETA is prepared by heating ethylenediamine or ethanolamine/ammonia mixtures over an oxide catalyst. This process gives a variety of amines, which are separated by distillation and sublimation.[2]


The reactivity and uses of TETA are similar to those for the related polyamines ethylenediamine and diethylenetriamine. It was primarily used as a crosslinker (“hardener”) in epoxy curing.[2]

The hydrochloride salt of TETA, referred to as trientine hydrochloride, is a chelating agent that is used to bind and remove copper in the body to treat Wilson’s disease, particularly in those who are intolerant to penicillamine. Some recommend trientine as first-line treatment, but experience with penicillamine is more extensive.[3]

Coordination chemistry

TETA is a tetradentate ligand in coordination chemistry, where it is referred to as trien.[4] Octahedral complexes of the type M(trien)Cl3 can adopt several diastereomeric structures, most of which are chiral.[5]

Trientine, chemically known as triethylenetetramine or N,N’-bis(2-aminoethyl)-l,2-ethanediamine belongs to the class of polyethylene polyamines. Trientine dihydrochloride is a chelating agent which is used to bind and remove copper in the body in the treatment of Wilson’s disease.

Image result for TRIENTINE

Trientine dihydrochloride (1)

Trientine dihydrochloride formulation, developed by Aton with the proprietary name SYPRINE, was approved by USFDA on November 8, 1985 for the treatment of patients with Wilson’s disease, who are intolerant to penicillamine. Trientine dihydrochloride, due to its activity on copper homeostasis, is being studied for various potential applications in the treatment of internal organs damage in diabetics, Alzheimer’s disease and cancer.

Various synthetic methods for preparation of triethylenetetramine (TETA) and the corresponding dihydrochloride salt have been disclosed in the prior art.

U.S. 4,806,517 discloses the synthesis of triethylenetetramine from ethylenediamine and monoethanolamine using Titania supported phosphorous catalyst while U.S. 4,550,209 and U.S. 5,225,599 disclose catalytic condensation of ethylenediamine and ethylene glycol for the synthesis of linear triethylenetetramine using catalysts like zirconium trimethylene diphosphonate, or metatungstate composites of titanium dioxide and zirconium dioxide.

U.S. 4,503,253 discloses the preparation of triethylenetetramine by reaction of an alkanolamine compound with ammonia and an alkyleneamine having two primary amino groups in the presence of a catalyst, such as supported phosphoric acid wherein the support is comprised of silica, alumina or carbon.

The methods described above for preparation of triethylenetetramine require high temperatures and pressure. Further, due to the various possible side reactions and consequent associated impurities, it is difficult to control the purity of the desired amine.

CN 102924289 discloses a process for trientine dihydrochloride comprising reduction of Ν,Ν’-dibenzyl-,N,N’-bis[2-(l,3-dioxo-2H-isoindolyl)ethyl]ethanediamine using hydrazine hydrate to give N,N’-dibenzyl-,N,N’-bis(2-aminoethyl)ethanediamine, which, upon condensation with benzyl chloroformate gave N,N’-dibenzyl-,N,N’-bis[2-(Cbz-amino)ethyl]ethanediamine, and further reductive deprotection to give the desired compound.

CS 197,093 discloses a process comprising reaction of triethylenetetramine with concentrated hydrochloric acid to obtain the crystalline tetrahydrochlonde salt. Further reaction of the salt with sodium ethoxide in solvent ethanol, filtration of the solid sodium chloride which is generated in the process, followed by slow cooling and crystallization of the filtrate provided the dihydrochloride salt. Optionally, aqueous solution of the tetrahydrochloride salt was passed through a column of an anion exchanger and the eluate containing free base was treated with a calculated amount of the tetrahydrochloride, evaporated, and the residue was crystallized from aqueous ethanol to yield the dihydrochloride salt.

The process is quite circuitous and cumbersome, requiring use of strong bases, filtration of sodium chloride and results in yields as low as 60%.

US 8,394,992 discloses a method for preparation of triethylenetetramine dihydrochloride wherein tertiary butoxycarbonyl (boc) protected triethylenetetramine is first converted to its tetrahydrochloride salt using large excess of hydrochloric acid in solvent isopropanol, followed by treatment of the resulting tetrahydrochloride salt with a strong base like sodium alkoxide to produce the amine free base (TETA) and sodium chloride salt in anhydrous conditions. The free amine is extracted with tertiary butyl methyl ether (TBME), followed by removal of sodium chloride salt and finally the amine free base TETA is treated with hydrochloric acid in solvent ethanol to give trientine hydrochloride salt.





Example 1: Preparation of 2-([2-[cyanomethyl]-t-butyloxycarbonylamino]ethyl- 1-butyloxy carbonylamino)acetonitrile (5)

Potassium carbonate (481.9 g) was added to a stirred mixture of ethylenediamine (100.0 g) in acetonitrile (800 ml) and cooled to around 10°C. Chloroacetonitrile (263.8 g) was gradually added at same temperature and stirred at 25-30°C, till completion of the reaction, as monitored by HPLC. The mixture was cooled to 5-15°C and Boc-anhydride (762. lg) was added to it, followed by stirring at the same temperature. The temperature was raised to 25-30°C and the mass was stirred till completion of the reaction, as monitored by HPLC.

The reaction mass was filtered and the filtrate was concentrated. Toluene was added to the residue, and the mixture was heated to around 70°C followed by cooling and filtration to give 2-([2-[cyanomethyl)-t-butyloxycarbonylamino]ethyl-t-butyloxycarbonylamino) acetonitrile (5).

Yield: 506.8 g

% Yield: 89.9 %

Example 2: Preparation of t-butyl( N-2-aminoethyl)N-([2-[(2-aminoethyl)t-butyloxy)carbonylamino] ethyl) carbamate (6)

Raney nickel (120.0 g) in isopropanol (100 ml) was charged into an autoclave, followed by a mixture of Compound 5 (200 g) in isopropanol (400 ml). Cooled ammonia solution prepared by purging ammonia gas in 1400 ml isopropanol, equivalent to 125 g ammonia was gradually charged to the autoclave and the reaction was carried out around 15-25°C under hydrogen pressure of 2-5 Kg/cm2.

After completion of the reaction, as monitored by HPLC, the mass was filtered, concentrated, and methyl tertiary butyl ether was added to the residue. The mixture was heated to around 50°C, followed by cooling of the mass, stirring, optional seeding with compound 6 and filtration to give tertiary butyl-(N-2-aminoethyl)N-([2-[(2-aminoethyl)-(tert-butyloxy) carbonylamino] ethyl) carbamate.

Yield: 174 g

%Yield: 85 %

Example 3: Preparation of triethylenetetramine dihydrochloride (1)

Concentrated hydrochloric acid (121.5 g) was gradually added to a stirred mixture of tertiary-butyl-N-(2-aminoethyl)-N-2-[(2-aminoethyl)-(tert-butoxy) carbonyl] amino] ethyl} carbamate (Compound 6, 200.0 g) and water (1400 ml) at 20-30°C. The reaction mixture was heated in the temperature range of 100-105°C till completion of the reaction, as monitored by HPLC, with optionally distilling out water, if so required.

The reaction mass was concentrated and ethanol (600 ml) was added to the residue, followed by heating till a clear solution was obtained. The reaction mixture was gradually cooled with stirring, filtered and dried to provide triethylenetetramine dihydrochloride (1).

Yield: 88.9 g, (70 %)

Purity : > 99%


Trientine was said to be used in the synthesis of benzylidene-(2-{3-[2-(benzylidene-amino)-ethyl]-2-phenyl-imidazolidin-1-yl}-ethyl)-amine in French Patent No. FR2810035 to Guilard et al. Cetinkaya, E., et al., “Synthesis and characterization of unusual tetraminoalkenes,” J. Chem. Soc. 5:561-7 (1992), is said to be directed to synthesis of benzylidene-(2-{3-[2-(benzylidene-amino)-ethyl]-2-phenyl-imidazolidin-1-yl}-ethyl)-amine from trientine, as is Araki T., et al., “Site-selective derivatization of oligoethyleneimines using five-membered-ring protection method,” Macromol., 21:1995-2001 (1988). Triethylenetetramine may reportedly also be used in the synthesis of N-methylated triethylenetetramine, as reported in U.S. Pat. No. 2,390,766, to Zellhoefer et al.

Synthesis of polyethylenepolyamines, including triethylenetetramines, from ethylenediamine and monoethanolamine using pelleted group IVb metal oxide-phosphate type catalysts was reported by Vanderpool et al. in U.S. Pat. No. 4,806,517. Synthesis of triethylenetetramine from ethylenediamine and ethanolamine was also proposed in U.S. Pat. No. 4,550,209, to Unvert et al. U.S. Pat. No. 5,225,599, to King et al. is said to be directed to the synthesis of linear triethylene tetramine by condensation of ethylenediamine and ethylene glycol in the presence of a catalyst. Joint production of triethylenetetramine and 1-(2-aminoethyl)-aminoethyl-piperazine was proposed by Borisenko et al. in U.S.S.R. Patent No. SU1541204. U.S. Pat. No. 4,766,247 and European Patent No. EP262562, both to Ford et al., reported the preparation of triethylenetetramine by reaction of an alkanolamine compound, an alkaline amine and optionally either a primary or secondary amine in the presence of a phosphorous containing catalyst, for example phosphoric acid on silica-alumina or Group IIIB metal acid phosphate, at a temperature from about 175° C. to 400° C. under pressure. These patents indicate that the synthetic method used therein was as set forth in U.S. Pat. No. 4,463,193, to Johnson. The Ford et al. ‘247 patent is also said to be directed to color reduction of polyamines by reaction at elevated temperature and pressure in the presence of a hydrogenation catalyst and a hydrogen atmosphere. European Patent No. EP450709 to King et al. is said to be directed to a process for the preparation of triethylenetetramine and N-(2-aminoethyl)ethanolamine by condensation of an alkylenamine and an alkylene glycol in the presence of a condensation catalyst and a catalyst promoter at a temperature in excess of 260° C.

Russian Patent No. RU2186761, to Zagidullin, proposed synthesis of diethylenetriamine by reaction of dichloroethane with ethylenediamine. Ethylenediamine has previously been said to have been used in the synthesis of N-carboxylic acid esters as reported in U.S. Pat. No. 1,527,868, to Hartmann et al.

Japanese Patent No. 06065161 to Hara et al. is said to be directed to the synthesis of polyethylenepolyamines by reacting ethylenediamine with ethanolamine in the presence of silica-treated Nb205 supported on a carrier. Japanese Patent No. JP03047154 to Watanabe et al., is said to be directed to production of noncyclic polyethylenepolyamines by reaction of ammonia with monoethanolamine and ethylenediamine. Production of non-cyclic polyethylenepolyamines by reaction of ethylenediamine and monoethanolamine in the presence of hydrogen or a phosphorous-containing substance was said to be reported in Japanese Patent No. JP03048644. Regenerative preparation of linear polyethylenepolyamines using a phosphorous-bonded catalyst was proposed in European Patent No. EP115,138, to Larkin et al.

A process for preparation of alkyleneamines in the presence of a niobium catalyst was said to be provided in European Patent No. 256,516, to Tsutsumi et al. U.S. Pat. No. 4,584,405, to Vanderpool, reported the continuous synthesis of essentially noncyclic polyethylenepolyamines by reaction of monoethanolamine with ethylenediamine in the presence of an activated carbon catalyst under a pressure between about 500 to about 3000 psig., and at a temperature of between about 200° C. to about 400° C. Templeton, et al., reported on the preparation of linear polyethylenepolyamides asserted to result from reactions employing silica-alumina catalysts in European Patent No. EP150,558.

Production of triethylenetetramine dihydrochloride was said to have been reported in Kuhr et al., Czech Patent No. 197,093, via conversion of triethylenetetramine to crystalline tetrahydrochloride and subsequently to triethylenetetramine dihydrochloride. “A study of efficient preparation of triethylenetetramine dihydrochloride for the treatment of Wilson’s disease and hygroscopicity of its capsule,” Fujito, et al., Yakuzaigaku, 50:402-8 (1990), is also said to be directed to production of triethylenetetramine.

Preparation of triethylenetetramine salts used for the treatment of Wilson’s disease was said to be reported in “Treatment of Wilson’s Disease with Triethylene Tetramine Hydrochloride (Trientine),” Dubois, et al., J. Pediatric Gastro. & Nutrition, 10:77-81 (1990); “Preparation of Triethylenetetramine Dihydrochloride for the Treatment of Wilson’s Disease,” Dixon, et al., Lancet, 1(1775):853 (1972); “Determination of Triethylenetetramine in Plasma of Patients by High-Performance Liquid Chromatography,” Miyazaki, et al., Chem. Pharm. Bull., 38(4):1035-1038 (1990); “Preparation of and Clinical Experiences with Trien for the Treatment of Wilson’s Disease in Absolute Intolerance of D-penicillamine,” Harders, et al., Proc. Roy. Soc. Med., 70:10-12 (1977); “Tetramine cupruretic agents: A comparison in dogs,” Allen, et al., Am. J. Vet. Res., 48(1):28-30 (1987); and “Potentiometric and Spectroscopic Study of the Equilibria in the Aqueous Copper(II)-3,6-Diazaoctane-1,8-diamine System,” Laurie, et al., J.C.S. Dalton, 1882 (1976).

Preparation of Triethylenetetramine Salts by Reaction of Alcohol Solutions of Amines and acids was said to be reported in Polish Patent No. 105793, to Witek. Preparation of triethylenetetramine salts was also asserted in “Polycondensation of polyethylene polyamines with aliphatic dicarboxylic acids,” Witek, et al., Polimery, 20(3):118-119 (1975).

Baganz, H., and Peissker, H., Chem. Ber., 1957; 90:2944-2949; Haydock, D. B., and Mulholland, T. P. C., J. Chem. Soc., 1971; 2389-2395; and Rehse, K., et al., Arch. Pharm., 1994; 393-398, report on Strecker syntheses. Use of Boc and other protecting groups has been described. See, for example, Spicer, J. A. et al., Bioorganic & Medicinal Chemistry, 2002; 10: 19-29; Klenke, B. and Gilbert, I. H., J. Org. Chem., 2001; 66: 2480-2483.

FIG. 6 shows an 1H-NMR spectrum of a triethylenetetramine hydrochloride salt in D2O, as synthesized in Example 3. NMR values include a frequency of 400.13 Mhz, a 1H nucleus, number of transients is 16, points count of 32768, pulse sequence of zg30, and sweep width of 8278.15 H

Image result for TRIENTINE


Method of purification: Dissolve Trientine Hydrochloride in water while warming, and recrystallize by addition of ethanol (99.5). Or dissolve Trientine Hydrochloride in water while warming, allow to stand after addition of activated charcoal in a cool and dark place for one night, and filter. To the filtrate add ethanol (99.5), allow to stand in a cool and dark place, and recrystallize. Dry the crystals under reduced pressure not exceeding 0.67 kPa at 409C until ethanol odor disappears.


  1.  “Ethyleneamines” (PDF). Huntsman. 2007.
  2. ^ Jump up to:a b Eller, K.; Henkes, E.; Rossbacher, R.; Höke, H. (2005). “Amines, Aliphatic”. Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a02_001.
  3. Jump up^ Roberts, E. A.; Schilsky, M. L. (2003). “A practice guideline on Wilson disease” (pdf). Hepatology. 37 (6): 1475–1492. doi:10.1053/jhep.2003.50252. PMID 12774027.
  4. Jump up^ von Zelewsky, A. (1995). Stereochemistry of Coordination Compounds. Chichester: John Wiley. ISBN 047195599X.
  5.  Utsuno, S.; Sakai, Y.; Yoshikawa, Y.; Yamatera, H. (1985). “Three Isomers of the Trans-Diammine-[N,N′-bis(2-Aminoethyl)-1,2-Ethanediamine]-Cobalt(III) Complex Cation”. Inorganic Syntheses. 23: 79–82. doi:10.1002/9780470132548.ch16.
Skeletal formula of triethylenetetramine
Ball and stick model of triethylenetetramine
Spacefill model of triethylenetetramine
Other names

N,N’-Bis(2-aminoethyl)ethane-1,2-diamine; TETA; Trien; Trientine (INN); Syprine (brand name)
3D model (Jmol)
ECHA InfoCard 100.003.591
EC Number 203-950-6
MeSH Trientine
RTECS number YE6650000
UN number 2259
Molar mass 146.24 g·mol−1
Appearance Colorless liquid
Odor Fishy, ammoniacal
Density 982 mg mL−1
Melting point −34.6 °C; −30.4 °F; 238.5 K
Boiling point 266.6 °C; 511.8 °F; 539.7 K
log P 1.985
Vapor pressure <1 Pa (at 20 °C)
376 J K−1 mol−1 (at 60 °C)
A16AX12 (WHO)
GHS pictograms The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
H312, H314, H317, H412
P273, P280, P305+351+338, P310
Corrosive C
R-phrases R21, R34, R43, R52/53
S-phrases (S1/2), S26, S36/37/39, S45
Flash point 129 °C (264 °F; 402 K)
Lethal dose or concentration (LD, LC):
  • 550 mg kg−1 (dermal, rabbit)
  • 2.5 g kg−1 (oral, rat)
Related compounds
Related amines
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

///////////////TRIENTINE, 112-24-3, 曲恩汀 , KD-034 , MK-0681, MK-681, TECZA, TETA, TJA-250, Orphan drug



Calcifediol, カルシフェジオール

Skeletal formula of calcifediol



Ro 8-8892
U 32070E
(3S,5Z,7E,20R)-9,10-Secocholesta-5,7,10-trien-3,25-diol [German] [ACD/IUPAC Name]
(3S,5Z,7E,20R)-9,10-Secocholesta-5,7,10-triene-3,25-diol [ACD/IUPAC Name]
(3S,5Z,7E,20R)-9,10-Sécocholesta-5,7,10-triène-3,25-diol [French] [ACD/IUPAC Name]
19356-17-3 [RN]
1H-indene-1-pentanol, octahydro-4-[(2Z)-2-[(5S)-5-hydroxy-2-methylenecyclohexylidene]ethylidene]-a,a,e,7a-tetramethyl-, (eR,1R,3aS,4E,7aR)-
25-(OH)Vitamin D3
25-hydroxy Vitamin D3
25-hydroxyvitamin D
Molecular form.: C₂₇H₄₄O₂
Appearance: White to Off-White Solid
Melting Point: 75-93ºC
Mol. Weight: 400.64

Calcifediol (INN), also known as calcidiol, 25-hydroxycholecalciferol, or 25-hydroxyvitamin D (abbreviated 25(OH)D),[1] is a prehormone that is produced in the liver by hydroxylation of vitamin D3 (cholecalciferol) by the enzyme cholecalciferol 25-hydroxylase which was isolated by Michael F. Holick. Physicians worldwide measure this metabolite to determine a patient’s vitamin D status.[2] At a typical daily intake of vitamin D3, its full conversion to calcifediol takes approximately 7 days.[3]

Calcifediol is then converted in the kidneys (by the enzyme 25(OH)D-1α-hydroxylase) into calcitriol (1,25-(OH)2D3), a secosteroid hormone that is the active form of vitamin D. It can also be converted into 24-hydroxycalcidiol in the kidneys via 24-hydroxylation.[4][5]


Blood test

In medicine, a 25-hydroxy vitamin D (calcifediol) blood test is used to determine how much vitamin D is in the body.[6] The blood concentration of calcifediol is considered the best indicator of vitamin D status.[7]

This test can be used to diagnose vitamin D deficiency, and it is indicated in patients with high risk for vitamin D deficiency and when the results of the test would be used as supporting evidence for beginning aggressive therapies.[8] Patients with osteoporosis, chronic kidney disease, malabsorption, obesity, and some other infections may be high risk and thus have greater indication for this test.[8] Although vitamin D deficiency is common in some populations including those living at higher latitudes or with limited sun exposure, the 25(OH)D test is not indicated for entire populations.[8] Physicians may advise low risk patients to take over-the-counter vitamin D in place of having screening.[8]

It is the most sensitive measure,[9] though experts have called for improved standardization and reproducibility across different laboratories.[7] According to MedlinePlus, the normal range of calcifediol is 30.0 to 74.0 ng/mL.[6] The normal range varies widely depending on several factors, including age and geographic location. A broad reference range of 20–150 nmol/L (8-60 ng/ml) has also been suggested,[10] while other studies have defined levels below 80 nmol/L (32 ng/ml) as indicative of vitamin D deficiency.[11]

US labs generally report 25(OH)D levels as ng/mL. Other countries often use nmol/L. Multiply ng/mL by 2.5 to convert to nmol/L.

Clinical significance

Increasing calcifediol levels are associated with increasing fractional absorption of calcium from the gut up to levels of 80 nmol/L (32 ng/mL).[citation needed]Urinary calcium excretion balances intestinal calcium absorption and does not increase with calcifediol levels up to ~400 nmol/L (160 ng/mL).[12]

A study by Cedric F. Garland and Frank C. Garland of the University of California, San Diego analyzed the blood from 25,000 volunteers from Washington County, Maryland, finding that those with the highest levels of calcifediol had a risk of colon cancer that was one-fifth of typical rates.[13] However, randomized controlled trials failed to find a significant correlation between vitamin D supplementation and the risk of colon cancer.[14]

A 2012 registry study of the population of Copenhagen, Denmark, found a correlation between both low and high serum levels and increased mortality, with a level of 50–60 nmol/L being associated with the lowest mortality. The study did not show causation.[15][16]


Regioselective Hydroxylation in the Production of 25-Hydroxyvitamin D by Coprinopsis cinerea Peroxygenase
ChemCatChem (2015), 7, (2), 283-290

1H NMR 500 MHz, CDCl3: δ= 0.55 (3 H, s, 18-H), 0.94 (1H, d, J= 6.5 Hz, 21-H), 1.06 (1H, m, 22-H), 1.22 (3 H, s, 26-H), 1.22 (3 H, s, 27-H), 1.23 (1H, m, 23-H), 1.27 (1H, m, 16-H), 1.28 (1H, m, 14-H), 1.29 (1H, m, 12-H), 1.37 (1H, m, 22-H), 1.38 (1H, m, 20-H), 1.39 (1H, m, 24-H), 1.42 (1H, m, 23-H), 1.44 (1H, m, 24-H), 1.47 (2 H, m, 11-H), 1.53 (1H, m, 15-H), 1.66 (1H, m, 15-H), 1.67 (1H, m, 2-H), 1.67 (1H, m, 9-H), 1.87 (1H, m, 16-H), 1.92 (1H, m, 2-H), 1.98 (1H, m, 17-H), 2.06 (1H, m, 12-H), 2.17 (1H, m, 1-H), 2.40 (1H, m, 1-H), 2.57 (1H, dd, J= 3.7, 13.1Hz, 4-H), 2.82 (1H, m, 9-H), 3.95 (1H, bm, 3-H), 4.82 (1H, m, 19-H), 5.05 (1H, m, 19-H), 6.03 (1H, d, J=11.2 Hz, 7-H), 6.23 ppm (1H, d, J= 11.2 Hz, 6-H).

13 C NMR 500 MHz, CDCl3: δ = 12.2 (C-18), 19.0 (C-21), 21.0 (C-23), 22.4 (C-11), 23.7 (C-15), 27.8 (C-16), 29.2 (C-9), 29.4 (C-27), 29.5 (C-26), 32.1 (C-1), 35.3 (C-2), 36.3 (C-20), 36.6 (C-22), 40.7 (C-12), 44.6 (C-24), 46.0 (C-13), 46.1 (C-4), 56.5 (C-17), 56.7 (C-14), 69.4 (C-3), 71.3 (C-25), 112.6 (C-19), 117.7 (C-7), 122.2 (C-6), 135.2 (C-5), 142.4 (C-8), 145.3 ppm (C-10).


From Organic & Biomolecular Chemistry, 10(27), 5205-5211; 2012!divAbstract

An efficient, two-stage, continuous-flow synthesis of 1α,25-(OH)2-vitamin D3 (activated vitamin D3) and its analogues was achieved. The developed method afforded the desired products in satisfactory yields using a high-intensity and economical light source, i.e., a high-pressure mercury lamp. In addition, our method required neither intermediate purification nor high-dilution conditions.

Graphical abstract: Continuous-flow synthesis of activated vitamin D3 and its analogues

1H NMR(400 MHz, CDCl3): δ 8.13 (m, 2H), 7.68 (m, 2H), 6.64 (d, J = 8.3 Hz, 1H), 6.25 (d, J = 8.3 Hz, 1H), 5.19 (m, 2H), 3.93 (dd, J = 12.7, 8.2, 1H), 3.88 (dd, J = 14.6, 4.9 Hz, 1H), 3.58 (m, 1H), 1.02 (s, 3H), 1.02 (d, J = 6.8 Hz, 3H), 0.90 (d, J = 6.8 Hz, 3H), 0.86 (s, 9H), 0.80-0.84 (m, 9H), 0.09 (s, 3H), 0.00 (s, 3H)

13C NMR  (100 MHz, CDCl3): δ 161.8, 159.6, 138.5, 135.3, 132.6, 132.5, 132.1, 130.6, 130.2, 128.7, 127.0, 126.5, 77.2, 68.5, 67.4, 67.1, 56.5, 50.6, 49.0, 44.2, 42.7, 40.4, 39.9, 39.3, 35.6, 34.7, 33.0, 30.5, 28.2, 25.9, 24.5, 21.9, 20.8, 19.9, 19.7, 18.5, 18.0, 17.4, 13.3, -4.4, -4.9

IR (neat): 2957, 2872, 1653, 1603, 1462, 1311, 1093, 837, 762 cm-1


Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles. [§ 1]



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|{{{bSize}}}px|alt=Vitamin D Synthesis Pathway]

Vitamin D Synthesis Pathway edit

  1. Jump up^ The interactive pathway map can be edited at WikiPathways: “VitaminDSynthesis_WP1531”.


  1. Jump up^ “Nomenclature of Vitamin D. Recommendations 1981. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN)” reproduced at the Queen Mary, University of London website. Retrieved 21 March 2010.
  2. Jump up^ Holick, MF; Deluca, HF; Avioli, LV (1972). “Isolation and identification of 25-hydroxycholecalciferol from human plasma”. Archives of Internal Medicine. 129 (1): 56–61. doi:10.1001/archinte.1972.00320010060005. PMID 4332591.
  3. Jump up^ Am J Clin Nutr 2008;87:1738–42 PMID 18541563
  4. Jump up^ Bender, David A.; Mayes, Peter A (2006). “Micronutrients: Vitamins & Minerals”. In Victor W. Rodwell; Murray, Robert F.; Harper, Harold W.; Granner, Darryl K.; Mayes, Peter A. Harper’s Illustrated Biochemistry. New York: Lange/McGraw-Hill. pp. 492–3. ISBN 0-07-146197-3. Retrieved December 10, 2008 through Google Book Search.
  5. Jump up^ Institute of Medicine (1997). “Vitamin D”. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, D.C: National Academy Press. p. 254. ISBN 0-309-06403-1.
  6. ^ Jump up to:a b “25-hydroxy vitamin D test: Medline Plus”. Retrieved 21 March 2010.
  7. ^ Jump up to:a b Heaney, Robert P (Dec 2004). “Functional indices of vitamin D status and ramifications of vitamin D deficiency”. American Journal of Clinical Nutrition. 80 (6): 1706S–9S. PMID 15585791.
  8. ^ Jump up to:a b c d American Society for Clinical Pathology, “Five Things Physicians and Patients Should Question”, Choosing Wisely: an initiative of the ABIM Foundation, American Society for Clinical Pathology, retrieved August 1, 2013, which cites
      • Sattar, N.; Welsh, P.; Panarelli, M.; Forouhi, N. G. (2012). “Increasing requests for vitamin D measurement: Costly, confusing, and without credibility”. The Lancet. 379 (9811): 95–96. doi:10.1016/S0140-6736(11)61816-3. PMID 22243814.
      • Bilinski, K. L.; Boyages, S. C. (2012). “The rising cost of vitamin D testing in Australia: Time to establish guidelines for testing”. The Medical Journal of Australia. 197 (2): 90. doi:10.5694/mja12.10561. PMID 22794049.
      • Lu, Chuanyi M. (May 2012). “Pathology consultation on vitamin D testing: Clinical indications for 25(OH) vitamin D measurement [Letter to the editor]”. American Journal Clinical Pathology. American Society for Clinical Pathology (137): 831–832., which cites
        • Arya, S. C.; Agarwal, N. (2012). “Pathology Consultation on Vitamin D Testing: Clinical Indications for 25(OH) Vitamin D Measurement”. American Journal of Clinical Pathology. 137 (5): 832. doi:10.1309/AJCP2GP0GHKQRCOE. PMID 22523224.
      • Holick, M. F.; Binkley, N. C.; Bischoff-Ferrari, H. A.; Gordon, C. M.; Hanley, D. A.; Heaney, R. P.; Murad, M. H.; Weaver, C. M. (2011). “Evaluation, Treatment, and Prevention of Vitamin D Deficiency: An Endocrine Society Clinical Practice Guideline”. Journal of Clinical Endocrinology & Metabolism. 96 (7): 1911–1930. doi:10.1210/jc.2011-0385. PMID 21646368.
  9. Jump up^ Institute of Medicine (1997), p. 259
  10. Jump up^ Bender, David A. (2003). “Vitamin D”. Nutritional biochemistry of the vitamins. Cambridge: Cambridge University Press. ISBN 0-521-80388-8. Retrieved December 10, 2008 through Google Book Search.
  11. Jump up^ Hollis BW (February 2005). “Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D”. J Nutr. 135 (2): 317–22. PMID 15671234.
  12. Jump up^ Kimball; et al. (2004). “Safety of vitamin D3 in adults with multiple sclerosis”. J Clin Endocrinol Metab. 86 (3): 645–51. PMID 17823429.
  13. Jump up^ Maugh II, Thomas H. “Frank C. Garland dies at 60; epidemiologist helped show importance of vitamin D: Garland and his brother Cedric were the first to demonstrate that vitamin D deficiencies play a role in cancer and other diseases.”, Los Angeles Times, August 31, 2010. Accessed September 4, 2010.
  14. Jump up^ Wactawski-Wende, J; Kotchen, JM, Women’s Health Initiative Investigators (Mar 9, 2006). “Calcium plus vitamin D supplementation and the risk of colorectal cancer.”. N Engl J Med. 354 (7): 684–96. doi:10.1056/NEJMoa055222. PMID 16481636. Retrieved December 28, 2013.
  15. Jump up^ “Too much vitamin D can be as unhealthy as too little” (Press release). University of Copenhagen. May 29, 2012. Retrieved 2015-05-27.
  16. Jump up^ Durup, D.; Jørgensen, H. L.; Christensen, J.; Schwarz, P.; Heegaard, A. M.; Lind, B. (May 9, 2012). “A Reverse J-Shaped Association of All-Cause Mortality with Serum 25-Hydroxyvitamin D in General Practice: The CopD Study”. The Journal of Clinical Endocrinology & Metabolism. Endocrine Society. 97 (8): 2644–2652. doi:10.1210/jc.2012-1176. Retrieved 2015-05-27.
Skeletal formula of calcifediol
Ball-and-stick model of the calcifediol molecule
IUPAC names

Other names

25-Hydroxyvitamin D3
19356-17-3 Yes
3D model (Jmol) Interactive image
ChEBI CHEBI:17933 
ChemSpider 4446820 
DrugBank DB00146 Yes
ECHA InfoCard 100.039.067
MeSH Calcifediol
PubChem 5283731
Molar mass 400.64 g/mol
A11CC06 (WHO)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).


Title: Calcifediol
CAS Registry Number: 19356-17-3
CAS Name: (3b,5Z,7E)-9,10-Secocholesta-5,7,10(19)-triene-3,25-diol
Additional Names: 25-hydroxyvitamin D3; 25-hydroxycholecalciferol; 25-HCC
Manufacturers’ Codes: U-32070E
Trademarks: Dedrogyl (DESMA); Didrogyl (Bruno); Hidroferol (FAES)
Molecular Formula: C27H44O2
Molecular Weight: 400.64
Percent Composition: C 80.94%, H 11.07%, O 7.99%
Literature References: The principal circulating form of vitamin D3, formed in the liver by hydroxylation at C-25: Ponchon, DeLuca, J. Clin. Invest. 48, 1273 (1969). It is the intermediate in the formation of 1a,25-dihydroxycholecalciferol, q.v., the biologically active form of vitamin D3 in the intestine. Identification in rat as an active metabolite of vitamin D3: Lund, DeLuca, J. Lipid Res. 7, 739 (1966); Morii et al., Arch. Biochem. Biophys. 120, 513 (1967). Evaluation of biological activity in comparison with vitamin D3: Blunt et al., Proc. Natl. Acad. Sci. USA 61, 717 (1968); ibid. 1503. Isoln from porcine plasma and establishment of structure: Blunt et al., Biochemistry 7, 3317 (1968). Synthesis: Blunt, DeLuca, ibid. 8, 671 (1969). Review of isoln, identification and synthesis: DeLuca, Am. J. Clin. Nutr. 22, 412 (1969). Review of bioassays: J. G. Haddad Jr., Basic Clin. Nutr. 2, 579-597 (1980).
Properties: uv max (ethanol): 265 nm (e 18000) (Blunt, DeLuca).
Absorption maximum: uv max (ethanol): 265 nm (e 18000) (Blunt, DeLuca)
Therap-Cat: Calcium regulator.
Keywords: Calcium Regulator.

/////////Calcifediol, カルシフェジオール



Balsalazide structure.svg


80573-04-2; Colazal; Balsalazide Disodium; AC1NSFNR; P80AL8J7ZP;
Molecular Formula: C17H15N3O6
Molecular Weight: 357.322 g/mol

(3E)-3-[[4-(2-carboxyethylcarbamoyl)phenyl]hydrazinylidene]-6-oxocyclohexa-1,4-diene-1-carboxylic acid


CAS Number 150399-21-6
Weight Average: 437.316
Monoisotopic: 437.08110308
Chemical Formula C17H17N3Na2O8

Balsalazide is an anti-inflammatory drug used in the treatment of inflammatory bowel disease. It is sold under the brand names Giazo, Colazal in the US and Colazide in the UK. It is also sold in generic form in the US by several generic manufacturers.

It is usually administered as the disodium salt. Balsalazide releases mesalazine, also known as 5-aminosalicylic acid, or 5-ASA,[1] in the large intestine. Its advantage over that drug in the treatment of ulcerative colitis is believed to be the delivery of the active agent past the small intestine to the large intestine, the active site of ulcerative colitis.

Balsalazide is an anti-inflammatory drug used in the treatment of Inflammatory Bowel Disease. It is sold under the name “Colazal” in the US and “Colazide” in the UK. The chemical name is (E)-5-[[-4-(2-carboxyethyl) aminocarbonyl] phenyl]azo] –2-hydroxybenzoic acid. It is usually administered as the disodium salt. Balsalazide releases mesalazine, also known as 5-aminosalicylic acid, or 5-ASA, in the large intestine. Its advantage over that drug in the treatment of Ulcerative colitis is believed to be the delivery of the active agent past the small intestine to the large intestine, the active site of ulcerative colitis.

Balsalazide disodium and its complete synthesis was first disclosed by Chan[18] in 1983, assigned to Biorex Laboratories Limited, England, claiming product ‘Balsalazide’ and process of its preparation. The synthesis involves converting 4-nitrobenzoyl chloride (6) to 4- nitrobenzoyl-β-alanine (7), hydrogenating with Pd/C (5%) in ethanol and isolating by adding diethyl ether to produce 4-aminobenzoyl-β-alanine (8). Thereafter, 4-aminobenzoyl-β-alanine (8) was treated with hydrochloric acid and sodium nitrite to generate N-(4-diazoniumbenzoyl)- β-alanine hydrochloride salt (9) which was reacted at low temperature with disodium salicylate to furnish Balsalazide disodium insitu which was added to dilute hydrochloric acid at low temperature to produce Balsalazide (1) (Scheme-1.1). Thus obtained Balsalazide was recrystallized with hot ethanol and converted to pharmaceutically acceptable salt (disodium salt).

Optimization of this diazonium salt based process was performed by Huijun et al[19] and reported the preparation of the title compound in 64.6% overall yield. Zhenhau et al[20] have synthesized 1 from 4-nitrobenzoic acid (12) via chlorination, condensation, hydrogenation, diazotization, coupling and salt formation with overall yield 73%. Li et al[21] have given product in 73.9% total yield starting from 4-nitrobenzoyl chloride (6), where as Yuzhu et al[22] confirmed chemical structure of Balsalazide disodium by elemental analysis, UV, IR, 1H-NMR and ESI-MS etc. Shaojie et al[23] have also followed same process for its preparation. Yujie et al[24] synthesized 1 in this way; preparation of 4-nitrobenzoyl-β-alanine (7) under microwave irradiation of 420 W at 52oC for 10sec., reduction in ethyl acetate in the presence of Pd/C catalyst then diazotization, coupling and salt formation. Eckardt et al[25] have developed a process for the preparation of Balsalazide which comprises, conversion of 4-aminobenzoyl-β-alanine (8) to 4-ammoniumbenzoyl-β-alanine sulfonate salt using a sulfonic acid in water. This was treated with aq. sodium nitrite solution at low temperature to generate 4-diazoniumbenzoyl-β-alanine sulfonate salt (11) which was quenched with aq. disodium salicylate to furnish Balsalazide disodium solution. This was further acidified to allow isolation of 1 and then conversion to disodium salt (Scheme-1.2) in 76% yield.

IR (KBr, cm-1 ): 3371 and 3039 (OH and NH), 1705 and 1699 (C=O), 1634 (C=O amide), 1590 and 1538 (C=C aromatic), 1464 and 1404 (aliphatic C-H), 1229 (C-N), 1073 (C-O), 773 and 738 (Ar-H out of plane bend). 1H NMR (DMSO-d6, 300 MHz, δ ppm): 2.54 (t, 2H), 3.50 (m, 2H), 6.95 (d, J = 8.8 Hz, 1H), 7.87 (d, J = 8.5 Hz, 2H), 8.02 (d, J = 8.5 Hz, 2H), 7.95 (dd, J = 8.8 Hz and 2.5 Hz, 1H), 8.34 (d, J = 2.5 Hz, 1H), 8.68 (t, J = 5.5 Hz, 1H), 12.12 (brs, 1H). MS m/z (ESI): 356 [(M-H)- ], Calculated; m/z 357.


Balsalazide synthesis: Biorex Laboratories, GB 2080796 (1986).

  1. Starting material is 4-aminohippuric acid, obtained by coupling para-aminobenzoic acid and glycine.
  2. That product is then treated with nitrous acid to give the diazonium salt.
  3. Reaction of this species with salicylic acid proceeds at the position para to the phenol to give balsalazide.

Sodium balsalazide (Balsalazide sodium)

Brief background information

Salt ATC Formula MM CAS
A07EC04 C 17 H 13 N 3 Na 2 O 6 401.29 g / mol 82101-18-6
(E) is the free acid A07EC04 C 17 H 15 N 3 O 6 357.32 g / mol 80573-04-2A


  • resolvent

Classes substance

  • β-alanine (3-aminopropionic acid)
    • m-aminobenzoic acid and esters and amides thereof
      • p-aminobenzoic acid and esters and amides thereof
        • azobenzene
          • salicylic acid

Synthesis Way

Synthesis of a)

Trade names

A country Tradename Manufacturer
United Kingdom Kolazid Shire
Italy Balzid Menarini
USA Kolazal Salix
Ukraine no no


  • capsules in 750 mg (as disodium salt)


Balsalazide disodium (1) represents an effective gastrointestinal anti-inflammatory compound useful as a medicament for the treatment of diseases such as ulcerative colitis. It is delivered intact to the colon where it is cleaved by bacterial azoreduction thereby generating 5-aminosalicylic acid as the medicinally active component.

Figure US07271253-20070918-C00001

To date, relatively few patents or literature articles have dealt with the preparation of Balsalazide or the disodium salt. For instance, U.S. Pat. No. 4,412,992 (Biorex, 1983) is the first patent that we uncovered that claims the compound Balsalazide and a strategy of how to prepare it which strategy is depicted in Scheme 1.

Figure US07271253-20070918-C00002

Optimization of this diazonium-based process is detailed in Shan et al., Zhongguo Yaowu Huaxue Zazhi, 11, 110 (2001) and Shi et al., Zhongguo Yiyao Gongye Zazhi, 34, 537 (2003).

Problems arise with the above strategy and the optimization process.

It is well-documented in the literature, for instance in Thermochimica Acta, 225, 201-211 (1993), that diazonium salts can be involved in serious accidents in their use. A possible cause of some of the diazonium salt related accidents is that, for one reason or another, an intermediate material appeared in crystalline form in the vessel of the reaction. As a result, a potentially severe drawback of the above processes occurs. Since the intermediate hydrochloride salt of 4-aminobenzoyl-β-alanine has poor solubility in water, it may pose a safety-risk in the subsequent diazotation reaction.

Also, it is well-known that certain diazonium salts possess high mechanical and heat sensitivity and that their decomposition goes through the liberation of non-condensable nitrogen gas which results in the possibility of runaway reactions and explosions. Obviously this safety consideration becomes more pertinent upon further scale-up.

Therefore, for commercial production of Balsalazide disodium, there was a need to develop a scalable and intrinsically better process

Example 1 Batch Process

N-(4-Aminobenzoyl)-β-alanine (100 g) was suspended in water (1300 mL) and methanesulfonic acid (115.4 g) was added to this mixture. The mixture was cooled to 10° C. and a solution of sodium nitrite (34.46 g) in water (200 mL) was added at a rate such that the temperature stayed below 12° C. The mixture was stirred for 30 min and added to an ice-cold solution of salicylic acid (69.65 g), sodium hydroxide (40.35 g) and sodium carbonate (106.9 g) in 1 L water at 7-12° C. After 3 hours at 10° C., the mixture was heated to 60-65° C. and acidified to pH 4.0-4.5 by the addition of hydrochloric acid. After a further 3 hours at 60-65° C., the mixture was cooled to ambient temperature, filtered, washed with water and dried in vacuo to yield Balsalazide. Yield ca. 90%. Balsalazide was transformed into its disodium salt in ca. 85% yield by treatment with aqueous NaOH solution followed by crystallization from n-propanol/methanol.

1H-NMR (400 MHz; D2O): δ=8.04 ppm (s); 7.67 ppm (d; J=8.2 Hz); 7.62 ppm (d, J=9.2 Hz); 7.53 ppm (d; J=8.2 Hz); 6.84 ppm (d; J=8.9 Hz); 3.57 ppm (t, J=7.1 Hz); 2.53 ppm (t; J=7.2 Hz).

Example 2 Continuous Process

For the continuous operation, a conventional dual-head metering pump (Ratiomatic by FMI) was used to deliver the mesylate solution and the aqueous sodium nitrite solution. The schematic diagram shown in FIG. 4 represents a set-up used for the continuous process. The first pump-head was set at 13.9 g/min whereas the second was set at 2.1 g/min. These flow rates offered a residence time of 9.4 min. The yield of the coupled intermediate from this residence time was 93%. The working solutions were prepared as follow:

The mesylate solution was prepared by the addition into a 2 L 3-necked round bottom flask, of N-(4-aminobenzoyl) β-alanine (120 g) followed by of DI water (1560 g) and methanesulfonic acid (177.5 g) (Batch appearance: clear solution). The first pump-head was primed with this solution and the flow rate was adjusted to 13.9 g/min.

The sodium nitrite solution was prepared by dissolving of sodium nitrite (41.8 g) in of DI water (240 g) (Batch appearance: clear solution). The second pump-head was primed with this solution and the flow rate adjusted to 2.1 g/min.

The quenching solution (sodium salicylate) was made by adding salicylic acid (139.3 g) to DI water (900 g) followed by of sodium carbonate (106.9 g) and 50% aqueous sodium hydroxide (80 g).

The diazotation reaction was performed in a 500 ml jacketed flow reactor with a bottom drain valve. The drain valve was set at 16 g/min. For reactor start-up, the flow reactor was charged with 150 mL of DI water as a working volume and cooled to the reactions initial temperature of 0-5° C. Concomitantly, the additions of the mesylate and sodium nitrite solutions were started and the bottom valve of the flow reactor was opened. During the diazotization, the flow rate of both solutions remained fixed and the temperature was kept below 12° C. and at the end of additions the pumps were stopped while the remaining contents in the flow reactor were drained into the quenching salicylic acid solution. Analysis of the contents in the quenching reactor indicated no signs of uncoupled starting material (diazonium compound). The reactor contents were heated to 60-65° C. for 2-3 hrs before adjusting the pH to precipitate the coupling product. This provided 191.5 g of product.

Cited Patent Filing date Publication date Applicant Title
US4412992 Jul 8, 1981 Nov 1, 1983 Biorex Laboratories Limited 2-Hydroxy-5-phenylazobenzoic acid derivatives and method of treating ulcerative colitis therewith
US6458776 * Aug 29, 2001 Oct 1, 2002 Nobex Corporation 5-ASA derivatives having anti-inflammatory and antibiotic activity and methods of treating diseases therewith
1 Chai, et al., Huaxi Yaoxue Zazhi, Jiangsu Institute of Materia Medica, Nanjing, China, 2004, 19(6), 431-433.
2 Shan, et al., Zhongguo Yaowu Huaxue Zazhi, Institute of Materia Medica, Peking Union Medical College, Beijing China, 2001, 11(2), 110-111.
3 Shi, et al., Zhongguo Yiyao Gongya Zazhi, Shanghai Institute of Pharmaceutical Industry, Shanghai, China, 2003, 34(11), 537-538.
4 Su, et al., Huaxue Gongye Yu Gongcheng (Tianjin, China), College of Chemistry and Chemical Eng., Donghua Univ., Shanghai, China, 2005, 22(4), 313-315.
5 Ullrich, et al., Decomposition of aromataic diazonium compounds, Thermochimica Acta, 1993, 225, 201-211.


  • Prakash, A; Spencer, CM: Drugs (DRUGAY) 1998 56 83- 89.
  • DE 3128819 (Biorex the Lab .; appl 07/21/1981;. GB -prior 07/21/1980, 07.07.1981.).


  1. Jump up^ Kruis, W.; Schreiber, I.; Theuer, D.; Brandes, J. W.; Schütz, E.; Howaldt, S.; Krakamp, B.; Hämling, J.; Mönnikes, H.; Koop, I.; Stolte, M.; Pallant, D.; Ewald, U. (2001). “Low dose balsalazide (1.5 g twice daily) and mesalazine (0.5 g three times daily) maintained remission of ulcerative colitis but high dose balsalazide (3.0 g twice daily) was superior in preventing relapses”. Gut. 49 (6): 783–789. doi:10.1136/gut.49.6.783. PMC 1728533Freely accessible. PMID 11709512.
1 to 5 of 5
Patent ID Patent Title Submitted Date Granted Date
US8232265 Multi-functional ionic liquid compositions for overcoming polymorphism and imparting improved properties for active pharmaceutical, biological, nutritional, and energetic ingredients 2007-04-26 2012-07-31
US2007213304 Use of Aminosalicylates in Diarrhoea-Predominent Irritable Bowel Syndrome 2007-09-13
US7119079 Bioadhesive pharmaceutical compositions 2004-07-22 2006-10-10
US6699848 Bioadhesive anti-inflammatory pharmaceutical compositions 2004-03-02
Balsalazide structure.svg
Clinical data
Trade names Colazal, Giazo
AHFS/ Monograph
MedlinePlus a699052
  • US: B (No risk in non-human studies)
ATC code A07EC04 (WHO)
Legal status
Legal status
  • UK: POM (Prescription only)
Pharmacokinetic data
Bioavailability <1%
Protein binding ≥99%
Biological half-life 12hr
CAS Number 80573-04-2 Yes
PubChem (CID) 5362070
DrugBank DB01014 Yes
ChemSpider 10662422 Yes
ChEBI CHEBI:267413 Yes
ECHA InfoCard 100.117.186
Chemical and physical data
Formula C17H15N3O6
Molar mass 357.318 g/mol
3D model (Jmol) Interactive image


Title: Balsalazide
CAS Registry Number: 80573-04-2
CAS Name: 5-[(1E)-[4-[[(2-Carboxyethyl)amino]carbonyl]phenyl]azo]-2-hydroxybenzoic acid
Additional Names: (E)-5-[[p-[(2-carboxyethyl)carbamoyl]phenyl]azo]-2-salicylic acid
Molecular Formula: C17H15N3O6
Molecular Weight: 357.32
Percent Composition: C 57.14%, H 4.23%, N 11.76%, O 26.87%
Literature References: Analog of sulfasalazine, q.v. Prodrug of 5-aminosalicylic acid where carrier molecule is 4-aminobenzoyl-b-alanine. Prepn: R. P. K. Chan, GB 2080796; idem, US 4412992 (1982, 1983 both to Biorex). Toxicology study and clinical metabolism: idem et al., Dig. Dis. Sci. 28, 609 (1983). Review of pharmacology and clinical efficacy in ulcerative colitis: A. Prakash, C. M. Spencer, Drugs 56, 83 (1998).
Properties: Crystals from hot ethanol, mp 254-255°.
Melting point: mp 254-255°
Derivative Type: Disodium salt dihydrate
CAS Registry Number: 150399-21-6; 82101-18-6 (anhydrous)
Manufacturers’ Codes: BX-661A
Trademarks: Colazal (Salix); Colazide (Shire)
Molecular Formula: C17H13N3Na2O6.2H2O
Molecular Weight: 437.31
Percent Composition: C 46.69%, H 3.92%, N 9.61%, Na 10.51%, O 29.27%
Properties: Orange to yellow microcrystalline powder, mp >350°. Nonhygroscopic. Freely sol in water, isotonic saline; sparingly sol in methanol, ethanol. Practically insol in organic solvents.
Melting point: mp >350°
Therap-Cat: Anti-inflammatory (gastrointestinal).
Keywords: Anti-inflammatory (Gastrointestinal); Anti-inflammatory (Nonsteroidal); Salicylic Acid Derivatives.




P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent.

Happy New Year's Eve from Google!

Glenmark Launches First and Only Generic Version of Zetia® (Ezetimibe) in the United States

Glenmark launches generic version of Zetia in US

Illustration Image Courtesy…

“We have launched ezetimibe, the first and only generic version of Zetia (Merck) in the United States for the treatment of high cholesterol,”……….



Glenmark Launches First and Only Generic Version of Zetia® in the United States 

Mumbai, India; December 12, 2016: Glenmark Pharmaceuticals Inc., USA today announced the availability of ezetimibe, the first and only generic version of ZETIA® (Merck) in the United States for the treatment of high cholesterol. The availability of ezetimibe is the result of a licensing partnership with Par Pharmaceutical, an Endo International plc operating company, with whom Glenmark will share profits. Glenmark and its partner, Endo will be entitled to 180 days of generic drug exclusivity for ezetimibe as provided for under section 505(j)(5)(B)(iv) of the FD&C Act.

Ezetimibe is indicated as adjunctive therapy to diet for the reduction of elevated total cholesterol (total-
C), low-density lipoprotein cholesterol (LDL-C), and apolipoprotein B (Apo B) in patients with primary
(heterozygous familial and non-familial) hyperlipidemia.
According to IMS Health data for the 12-month period ending October 2016, annual U.S. sales of Zetia®
10 mg were approximately $2.3 billion.
“Glenmark has a deep heritage of bringing safe, effective and affordable medicines to patients around
the world,” said Robert Matsuk, President of North America and Global API at Glenmark
Pharmaceuticals Ltd. “Our partnership with Par to bring the first generic version of ZETIA® to market
only underscores our joint commitment to bridging the gap between patients and the medicines they
need most.”
“We, along with our partners at Glenmark, are proud to be able to offer patients managing their
cholesterol levels the first generic version of ZETIA®,” said Tony Pera, President of Par Pharmaceutical.
“Par remains committed to providing patients access to high quality and affordable medicines.”
Glenmark’s current portfolio consists of 111 products authorized for distribution in the U.S. marketplace
and 64 ANDA’s pending approval with the U.S. Food and Drug Administration. In addition to these
internal filings, Glenmark continues to identify and explore external development partnerships to
supplement and accelerate the growth of its existing pipeline and portfolio.

About Glenmark Pharmaceuticals Ltd.:
Glenmark Pharmaceuticals Ltd. (GPL) is a research-driven, global, integrated pharmaceutical organization headquartered at Mumbai, India. It is ranked among the top 80 Pharma & Biotech companies of the world in terms of revenue (SCRIP 100 Rankings published in the year 2016). Glenmark is a leading player in the discovery of new molecules both NCEs (new chemical entity) and NBEs (new biological entity). Glenmark has several molecules in various stages of clinical development and is primarily focused in the areas of Inflammation [asthma/COPD, rheumatoid arthritis etc.] and Pain [neuropathic pain and inflammatory pain]. The company has a significant presence in the branded generics markets across emerging economies including India. GPL along with its subsidiaries operate 17 manufacturing facilities across four countries and has five R&D centers. The Generics business of Glenmark services the requirements of the US and Western European markets. The API business sells its products in over 80 countries including the US, EU, South America and India………

About Endo International plc:
Endo International plc (NASDAQ / TSX: ENDP) is a global specialty pharmaceutical company focused on improving patients’ lives while creating shareholder value. Endo develops, manufactures, markets and distributes quality branded and generic pharmaceutical products as well as over-the-counter medications though its operating companies. Endo has global headquarters in Dublin, Ireland, and U.S. headquarters in Malvern, PA. Learn more at


Dec 08, 2016, 08.16 PM | Source: CNBC-TV18 Glenmark to launch cholesterol drug Zetia in US on Dec 12 Glenmark was the first to file for the generic version of Zetia and it means that after the launch on December 12, only Glenmark and Merck will sell generic Zetia in the US market for the next 6 months. Glenmark   is launching cholesterol drug Zetia with 6 months exclusivity in the US on December 12. The company has partnered with Par Pharma on the drug and has a 50:50 profit sharing agreement with Par on Zetia. Glenmark was the first to file for the generic version of Zetia and it means that after the launch on December 12, only Glenmark and Merck will sell generic Zetia in the US market for the next 6 months. Total revenue estimated to be generated is around USD 400-500 million and post profit sharing with Par, Glenmark should make around USD 200-250 million.

Read more at:

////////////Glenmark,  Launches,  First,  Only,  Generic Version,  Zetia®,  United States, ezetimibe, par pharmaceutical, cholesterol, Endo International plc

ацетазоламид , أسيتازولاميد [, 乙酰唑胺 , ACETAZOLAMIDE

ChemSpider 2D Image | acetazolamide | C4H6N4O3S2

ацетазоламид ,  أسيتازولاميد [,  乙酰唑胺 ,
CAS 59-66-5
Acetamide, N-(5-(aminosulfonyl)-1,3,4-thiadiazol-2-yl)-
MW 222.245,MF  C4H6N4O3S2
Title: Acetazolamide
CAS Registry Number: 59-66-5
CAS Name: N-[5-(Aminosulfonyl)-1,3,4-thiadiazol-2-yl]acetamide
Additional Names: 5-acetamido-1,3,4-thiadiazole-2-sulfonamide; 2-acetylamino-1,3,4-thiadiazole-5-sulfonamide
Manufacturers’ Codes: 6063
Trademarks: Acetamox (Tobishi-Santen); Atenezol (Tsuruhara); Défiltran (Gallier); Diamox (Barr); Didoc (Sawai); Diuriwas (IFI); Donmox (Horita); Edemox (Wassermann); Fonurit (Chinoin); Glaupax (Erco)
Molecular Formula: C4H6N4O3S2
Molecular Weight: 222.25
Percent Composition: C 21.62%, H 2.72%, N 25.21%, O 21.60%, S 28.85%
Literature References: Carbonic anhydrase inhibitor. Prepn: R. O. Roblin, J. W. Clapp, J. Am. Chem. Soc. 72, 4890 (1950); J. W. Clapp, R. O. Roblin, US 2554816 (1951 to Am. Cyanamid). HPLC determn in pharmaceuticals: Z. S. Gomaa, Biomed. Chromatogr. 7, 134 (1993). Effect on retinal circulation: S. M. B. Rassam et al., Eye 7, 697 (1993). Clinical trial in postoperative elevation of intraocular pressure: I. D. Ladas et al., Br. J. Ophthalmol. 77, 136 (1993). Comprehensive description: J. Parasrampuria, Anal. Profiles Drug Subs. Excip. 22, 1-32 (1993). Review of efficacy in acute mountain sickness: L. D. Ried et al.,J. Wilderness Med. 5, 34-48 (1994).
Properties: Crystals from water, mp 258-259° (effervescence). Weak acid. pKa 7.2. Sparingly sol in cold water. Slightly sol in alcohol, acetone. Practically insol in carbon tetrachloride, chloroform, ether. Soly (mg/ml): polyethylene glycol-400 87.81; propylene glycol 7.44; ethanol 3.93; glycerin 3.65; water 0.72.
Melting point: mp 258-259° (effervescence)
pKa: pKa 7.2
Derivative Type: Sodium salt
CAS Registry Number: 1424-27-7
Trademarks: Vetamox (Am. Cyanamid)
Therap-Cat: Antiglaucoma; diuretic; in treatment of acute mountain sickness.
Therap-Cat-Vet: Diuretic.
Keywords: Antiglaucoma; Carbonic Anhydrase Inhibitor; Diuretic; Sulfonamide Derivatives.
Starting reaction occurs in-between hydrazine hydrate and ammonium thiocyanate that produces 1, 2-bis (thiocarbamoyl) hydrazine which on further treatment with phosgene undergoesrearrangements, particularly  molecular rearrangement through loss of ammonia to form 5-amino-2-mercapto-1, 3, 4-thiadiazole. Upon acylation of 5-amino-2-mercapto-1, 3, 4-thiadiazole gives a corresponding amide which on oxidation with aqueous chlorine affords the 2-sulphonyl chloride. The final step essentially consists of amidation by treatment with ammonia.





14N NQR, 1H NMR and DFT/QTAIM study of hydrogen bonding and polymorphism in selected solid 1,3,4-thiadiazole derivatives

Corresponding authors
a»Jozef Stefan« Institute, Jamova 39, 1000 Ljubljana, Slovenia
Fax: +386 1 2517281
Tel: +386 1 4766576
bFaculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
cFaculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
Phys. Chem. Chem. Phys., 2010,12, 13007-13019

DOI: 10.1039/C0CP00195C,!divAbstract

Graphical abstract: 14N NQR, 1H NMR and DFT/QTAIM study of hydrogen bonding and polymorphism in selected solid 1,3,4-thiadiazole derivatives

The 1,3,4-thiadiazole derivatives (2-amino-1,3,4-thiadiazole, acetazolamide, sulfamethizole) have been studied experimentally in the solid state by 1H–14N NQDR spectroscopy and theoretically by Density Functional Theory (DFT). The specific pattern of the intra and intermolecular interactions in 1,3,4-thiadiazole derivatives is described within the QTAIM (Quantum Theory of Atoms in Molecules)/DFT formalism. The results obtained in this work suggest that considerable differences in the NQR parameters permit differentiation even between specific pure association polymorphic forms and indicate that the stronger hydrogen bonds are accompanied by the larger η and smaller ν and e2Qq/h values. The degree of π-electron delocalization within the 1,3,4-thiadiazole ring and hydrogen bonds is a result of the interplay between the substituents and can be easily observed as a change in NQR parameters at N atoms. In the absence of X-ray data NQR parameters can clarify the details of crystallographic structure revealing information on intermolecular interactions.

////////////ацетазоламид ,  أسيتازولاميد [,  乙酰唑胺 , ACETAZOLAMIDE





Febuxostat; 144060-53-7; Uloric; Adenuric; Tei 6720; 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid;
Molecular Formula: C16H16N2O3S
Molecular Weight: 316.37484 g/mol

2-[3-cyano-4-(2-methylpropoxy)phenyl]-4-methyl-1,3-thiazole-5-carboxylic acid

Febuxostat is a thiazole derivative and inhibitor of XANTHINE OXIDASE that is used for the treatment of HYPERURICEMIA in patients with chronic GOUT.

CAS 144060-53-7

  • 2-[3-Cyano-4-(2-methylpropoxy)phenyl]-4-methyl-5-thiazolecarboxylic acid
  • 2-(3-Cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazolecarboxylic acid
  • FBX
  • Febugood
  • Feburic
  • Febutaz
  • TMX 67
  • Zurig


Febuxostat (INN; trade names Adenuric in Europe and New Zealand, Uloric in the US, Goturic in Latin America, Feburic in Japan) is a drug that inhibits xanthine oxidase, thus reducing production of uric acid in the body. It is used in the treatment of chronicgout and hyperuricemia.

Febuxostat was discovered by scientists at the Japanese pharmaceutical company Teijin in 1998. Teijin partnered the drug with TAP Pharmaceuticals in the US and Ipsen in Europe. Ipsen obtained marketing approval for febuxostat from the European Medicines Agency in April 2008, Takeda obtained FDA approval in February 2009, and Teijin obtained approval from the Japanese “Pharmaceuticals and Medical Devices Agency” in 2011.

Medical uses

Febuxostat is used to treat chronic gout and hyperuricemia.[2] National Institute for Health and Clinical Excellence concluded that febuxostat is more effective than standard doses of allopurinol, but not more effective than higher doses of allopurinol.[2]

Uloric 40 mg tablet

Febuxostat is in the US pregnancy category C; there are no adequate and well-controlled studies in pregnant women.[3]

Side effects

The adverse effects associated with febuxostat therapy include nausea, diarrhea, arthralgia, headache, increased hepatic serum enzyme levels and rash.[3][4]

Drug interactions

Febuxostat is contraindicated with concomitant use of theophylline and chemotherapeutic agents, namely azathioprine and 6-mercaptopurine, because it could increase blood plasma concentrations of these drugs, and therefore their toxicity.[3][5]

Mechanism of action

Febuxostat is a non-purine-selective inhibitor of xanthine oxidase.[3] It works by non-competitively blocking the molybdenum pterincenter which is the active site on xanthine oxidase. Xanthine oxidase is needed to successively oxidize both hypoxanthine andxanthine to uric acid. Hence, febuxostat inhibits xanthine oxidase, therefore reducing production of uric acid. Febuxostat inhibits both oxidized as well as reduced form of xanthine oxidase because of which febuxostat cannot be easily displaced from the molybdenum pterin site.[4]


Febuxostat was discovered by scientists at the Japanese pharmaceutical company Teijin in 1998.[6] Teijin partnered the drug withTAP Pharmaceuticals in the US and Ipsen in Europe.[7][8][9]

Ipsen obtained marketing approval for febuxostat from the European Medicines Agency in April 2008,[10] Takeda obtained FDA approval in February 2009,[11][12] and Teijin obtained approval from the Japanese authorities in 2011.[13] Ipsen exclusively licensed its European rights to Menarini in 2009.[14] Teijin partnered with Astellas for distribution in China and southeast Asia.[15][16]

Society and culture


In the UK, NICE has found that febuxostat has a higher cost/benefit ratio than allopurinol and on that basis recommended febuxostat as a second-line drug for people who cannot use allopurinol.[2]

Trade names

Febuxostat is marketed as Adenuric in Europe and New Zealand, Uloric in the US, Goturic and Goutex in Latin America, Feburic in Japan, and is generic in several countries and is available by many names in those countries.[1]

Febuxostat (Formula I) is an inhibitor of xanthine oxidase, which was discovered by the Japanese company Teijin Pharma Ltd and it is indicated for use in the treatment of hyperuricemia and chronic gout. Its chemical name is 2-(3-cyano-4-isobutoxyphenyl)-4-methyl- l,3-thiazole-5-carboxylic acid. It is marketed under the brand names Adenuric in Europe, Feburic in Japan and Uloric in USA and Canada.

In EP0513379B1 Febuxostat is prepared from 4-hydroxy-3-nitrobenzaldehyde, according to the following scheme.

This particular process suffers from major drawbacks. Not only it is very long, including seven steps from the starting material to the final product, but, most importantly, it employs the use of cyanides, which are extremely toxic reagents. Cyanide salts are likely to generate hydrocyanide, which sets a high amount of risk in an industrial scale process.

In Japanese patent JP06345724A(JP2706037B) the intermediate ethyl ester of Febuxostat is prepared from p-cyano-nitrobenzene, in three steps. Febuxostat may, then, be prepared by alkaline hydrolysis, according to prior art.


The use of extremely toxic potassium cyanide makes this process unsuitable for manufacturing purposes.

Route A

In Japanese patent JP3202607B Febuxostat ethyl ester is prepared, according to the above scheme, through two similar routes. Route A uses flash column chromatography for the purification of the hydroxylamine reaction product, while Route B suffers from low yield and the use of chlorinated solvents for recrystallization. In addition, the reaction solvent is, in both cases, formic acid which causes severe skin burns and eye damage to humans. Formic acid is also corrosive towards metal-based materials of construction (MOC), like stainless steel and nickel alloys, limiting the options, essentially, to glass reactors or vessels. The drawbacks of using this solvent are also related to the high volumes of formic acid required per batch, which hinder the waste treatment.

In CN101723915B focus is made to the improvement of the hydroxylamine reaction. Formic acid is replaced with dimethylformamide (DMF) and other solvents. However, according to widely used organic chemistry textbooks, such as March’s Advanced Organic Chemistry, pi 287, 6th edition, M. B. Smith and J. March, ISBN 0-471-72091-7, the mechanism of the reaction involves the formation of an oxime, upon the action of hydroxylamine, which further dehydrates to form a nitrile, with the aid of a suitable reagent, for example formic acid, or acetic anhydride. In the absence of such a reagent, it is expected that the reaction will, at least, not lead to completion, thereby leading to low yields and undesired impurity levels, namely the intermediate oxime. Such impurities, arising from the reactions of the process and which exhibit similar structure of the desired product, are often difficult to remove with common industrial techniques, e.g. crystallization.

In WO2010142653A1 the intermediate Febuxostat ethyl ester is prepared from 4-cyanophenol, through a five-step process. Febuxostat can be prepared from its respective ethyl ester via alkaline hydrolysis, as in the previous case.


1: patents US5614520 febuxostat synthetic process:

Figure CN104418823AD00031

2: Patent JP1994329647 febuxostat synthesis

Figure CN104418823AD00032
Figure CN104418823AD00041


Gout occurs because the body produces too much uric acid and renal clearance capacity decreased, uric acid accumulation in the body, leading to urate crystals deposited in the joints and organs. Therefore, it means the treatment of gout usually taken to be: to promote uric acid excretion and suppression of uric acid, and the use of appropriate measures to improve symptoms. Uric acid formation and purine metabolism, the final step in the purine metabolism, hypoxanthine generation xanthine xanthine oxidoreductase (XOR) effect, further generate uric acid, inhibit the activity of the enzyme can effectively reduce uric acid production. Febuxostat is currently the world’s newly developed XOR inhibitors, which act by highly selective to the oxidase, reduce uric acid synthesis, reduce uric acid levels, so as to effectively treat the disease ventilation.

Compared with the traditional treatment of gout drug allopurinol, febuxostat has obvious advantages: (1) allopurinol reduced the XOR only inhibit rather than febuxostat of oxidized and reduced form are XOR significant inhibition, thus reducing the role of uric acid, which is more powerful and lasting; (2) Since allopurinol is a purine analogue, the inevitable result of the purine and other activity related to the impact of pyridine metabolism. So allopurinol treatment should be repeated large doses of the drug to maintain a high level. Which also brought serious or even fatal adverse reactions due to drug accumulation due.Instead of febuxostat non-purine XOR inhibitors, so it has better security.

Document TMX-67. Drugs Fut2001, 26, I, 32, and EP0513379, US5614520, W09209279, public

The detailed preparation febuxostat. Using 3-nitro-4-hydroxybenzaldehyde as the starting material is first reacted with hydroxylamine hydrochloride, to give 3-nitro-4-hydroxybenzonitrile. In effect then HCl, reaction with thioacetamide to give 3-nitro-4-hydroxy-thiobenzamide. Closed loop then reacted with 2-chloro ethyl acetoacetate to give 2- (3_ nitro-4-hydroxyphenyl) methyl-5-thiazolyl -4_ carboxylic acid ethyl ester. Followed by potassium carbonate effect, isobutane is reacted with bromo, to give 2- (3_ nitro-4-isobutyloxyphenyl) -4-methyl-5-carboxylic acid ethyl ester. Under the catalytic action of palladium on carbon, hydrogen reduction to give 2- (3-amino-4-isobutyloxyphenyl) -4-methyl-5-thiazole carboxylic acid ethyl ester. Followed by diazotization with sodium nitrite occur, was added cuprous cyanide and potassium cyanide, to give 2- (3-cyano-4-isobutyloxyphenyl) -4-methyl-5-thiazolecarboxylic acid ethyl ester. Finally, under the effect of the hydrolysis of sodium hydroxide, to give the product 2- (3-cyano-4-isobutyloxyphenyl) -4-methyl – thiazole-5-carboxylic acid, to obtain febuxostat.The process route is as follows:

Figure CN102936230AD00041

This route in the preparation of febuxostat, there are many disadvantages: raw 3-nitro-4-hydroxybenzaldehyde in the country is difficult to buy; requires the use of palladium-carbon catalytic hydrogenation reaction under the factory equipment higher requirements, there is a certain danger; the cyano preparation, the need to use sodium nitrite diazotization, could easily lead to corrosion of equipment; the cyano preparation, the need to use toxic cyanide copper, potassium cyanide, pollution, higher risk.

Document JP1994329647, JP1998045733, US3518279 reported another synthesis of febuxostat

Methods. From 4-hydroxy-thiobenzamide as a starting material, and the cyclization reaction to give ethyl 2-bromo-acetyl occurred

2- (4_ hydroxyphenyl) -4_ methyl-5-carboxylic acid ethyl ester in polyphosphoric acid effect, HMTA (hexamethylene tetramine) reacts with 2- (3_ aldehyde – 4-hydroxyphenyl) methyl-5-thiazolyl -4_ carboxylic acid ethyl ester. Then two cases: the first case, the effect of potassium carbonate, is reacted with isobutane to give bromo-2- (4-isobutyloxyphenyl 3_ aldehyde) -4_-methyl-5- thiazole carboxylic acid ethyl ester, and then reacted with hydroxylamine hydrochloride to give 2- (3_-cyano-4-isobutyloxyphenyl) -4_-methyl-5-thiazole carboxylic acid ethyl ester; second case is the first with hydroxylamine hydrochloride to give 2- (3_ cyano-4-hydroxyphenyl) methyl-5-thiazolecarboxylic -4_ carboxylic acid ethyl ester, and then under the effect of potassium carbonate, and reacted with isobutane to give bromo-2- (3 _-cyano-4-isobutyloxyphenyl) -4-methyl-5-carboxylic acid ethyl ester.

Finally, under the effect of the hydrolysis of sodium hydroxide, to give the product 2- (3_-cyano-4-isobutyloxyphenyl) -4_ methyl – thiazole-5-carboxylic acid, i.e., to obtain febuxostat . The process route is as follows:

Figure CN102936230AD00051

This synthesis route febuxostat process, since the introduction of aldehyde HMTA in PPA (polyphosphoric acid) effect. So there are a lot of phosphorus wastewater, serious environmental pollution, but also because PPA has great viscosity, and therefore difficult to stir the production, operation is extremely inconvenient.

Document Heterocyclesl998, 47,2,857 JP1994345724 also reported the synthesis method of febuxostat, using p-nitrophenyl-carbonitrile as a starting material in the reaction with potassium cyanide in DMSO solvent, and then the carbonate lower potassium catalyzed reaction of isobutane and brominated 1,3-cyano-4-diisobutoxybenzene ether. By reaction with thioacetamide to afford

3-cyano-4-isobutyloxyphenyl thiobenzamide. Under heating, and 2-chloro ethyl acetoacetate, ring closure reaction occurs to give 2- (3-cyano-4-isobutyloxyphenyl) -4-methyl-5-carboxylic acid ethyl ester, and finally hydrolysis under the effect of sodium hydroxide, to give the product 2- (3-cyano-4-isobutyloxyphenyl) -4-methyl – thiazole-5-carboxylic acid, to obtain febuxostat.

The present invention febuxostat new technology system, comprising the steps of:

(1) 2-hydroxy-5-cyano – NaSH reacted with benzaldehyde to give 4-hydroxy-3- aldehyde thiobenzamide;

Figure CN102936230AD00061

(2) the step (I) to give 4-hydroxy-3-aldehyde thiobenzamide reaction with ethyl 2-halo-acetyl, closed

Ring to give 2- (3-aldehyde-4-hydroxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole;

Figure CN102936230AD00062

X is a halogen, preferably Cl or Br;

(3) the step (2) to give 2- (3-aldehyde-4-hydroxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole with hydroxylamine in formic acid in the reaction solution to give 2- (3- cyano-4-hydroxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole;

Figure CN102936230AD00063

(4) The step (3) to give 2- (3-cyano-4-hydroxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole isobutane with halo effect in potassium carbonate, to give 2- (3-aldehyde-4-isobutyloxyphenyl) -4-methyl-5-ethoxycarbonyl thiazole;

(5) in step (4) to give 2- (3-aldehyde-4-isobutyloxyphenyl) -4-methyl-5-ethoxycarbonyl-thiazol-off hydrolyzable ester group, to obtain a non-Tendon Disposition Tanzania.

[0011] Scheme of the method is as follows:

Figure CN102936230AD00071

X is halogen, may be Cl, Br;

Preparation 5 febuxostat Example

To a 500ml reaction flask was added 200ml of absolute ethanol, the product of Step 4 was added with stirring (60g, O. 174mol),

5% sodium hydroxide was added 100ml. Stirring heated to 40 degrees, until it is completely dissolved. 40 degrees heat, reaction 4h. The reaction by TLC tracking. After completion of the reaction, the reaction solution was added 10% hydrochloric acid to adjust the pH to 3, the precipitated solid was filtered. And dried to give a pale yellow solid. Dried over anhydrous recrystallized from methanol to give 31. 2g of white crystals, yield 56.7%.

 TLC monitoring of the reaction. Eluent: petroleum ether / ethyl acetate = 3: 1 Melting point:. 201 · 7 ~202 30C (literature value 201 ~202 ° C)

1H-NMR δ:. 1 01 (m, 6H), 2.06 (m, lH), 2.57 (m, 3 H), 3.96 (d, 2H), 7.30 (d, lH), 8.13 (m, 1H), 8. 19 (d, 1H);

MS (m / z):. 316 O (M +)

Infrared detection: 3550-3400cm_1; 2961, 2933,2874; 2227cm_1; 1680U604U511cm_1; 1425cm_1; 1296U283CHT1;

Elemental analysis for C, Η, N, S purified product actual measurement of the content of C, H, N, S content: C:. 60 57%, H:. 5 32%, N:. 8 86%, S: 10. 16%; theoretical value: In C16H16N203S calculated C: 60 74%, H: 510%, N: 885%, S: 1014%..


Facile OnePot Transformation of Arenes into Aromatic Nitriles …

Facile OnePot Transformation of Arenes into Aromatic Nitriles under MetalCyanideFree Conditions



synthesis  describes synthesis of febuxostat (I) from 4-hydroxybenzonitrile (II) in six stages. The synthesis shown is a short, concise route and does not require use of poisonous reagents such as KCN (14). Compound II was converted to 4-hydroxybenzothioamide (III) with 85% yield using NaHS in the presence of hydrated magnesium chloride as Lewis acid. Intermediate III, on cyclization with ethyl-2-chloroacetoacetate, gave thiazole ester (IV) with quantitative yield. In these two stages, the source of potential impurities was identified as an ortho isomer (i.e., 2-hydroxybenzonitrile), which can lead to Impurity VIII and subsequently to Impurity IX . Impurities VIII and IX can be controlled in starting material II with appropriate specification.

Figure 2
Figure 2: Impurities identified during the various stages of synthesis of febuxostat.

The ortho formylation of hydroxyl compound IV by using Duff condition (hexamine/TFA) gave aldehyde V (15). The major impurity identified in this reaction was dialdehyde X. Although we have used only 1.0 equivalence of hexamine with respect to Compound IV, the dialdehyde X impurity was formed to a 5-10% ratio in only 2.5 h. It is, therefore, impossible to get rid of this impurity during the reaction, and only effective recrystallization will eliminate it. Impurity X was minimized (≤ 2%) by recrystallization using IPA/H2O (3:5) to get aldehyde V with 50% yield and & #8805; 97% HPLC purity.

Aldehyde V, on alkylation with isobutyl bromide in the presence of potassium carbonate base, gave compound VI with 90% yield. In this stage, Impurities XI and XII were alkylations of carryover Compound IV and dialdehyde, respectively. Two more isomeric impurities n-butyl-aldehyde XIII and 1-methyl propyl-aldehyde XIV were also identified in this stage. Both isomeric impurities can be controlled with appropriate specification for isobutyl bromide. The reaction of Compound VI with hydroxylamine hydrochloride and sodium formate in formic acid at reflux temperature gave Compound VII with 85% yield. Impurities XIII and XIV will also carry forward to impurities n-butyl-nitrile XV and 1-methyl propyl-nitrile XVI, respectively.

In the final step, Compound VII was hydrolyzed using sodium hydroxide in a MeOH:THF:H2O (1:1:1) solvent combination to yield febuxostat (85%). During saponification, methyl ester Impurity XVII was identified via trans-esterification. Its hydrolysis was comparatively slower than its ethyl isomer VII. One way to avoid Impurity XVII is to replace methanol with ethanol. Carryover impurities XI, XV, and XVI were also hydrolyzed to their respective acid derivatives impurities XVIII, XIX, and XX. However, the acid derivatives of impurities X and XII were unexpectedly absent as impurities. It is believed that, because they were present in low concentrations during workup, they were eliminated in the mother liquor. Two additional impurities, amide XXI and diacid XXII, formed by the side reaction of the febuxostat nitrile group with sodium hydroxide, were identified during saponification. The amide XXI and diacid XXII impurities can be controlled by using appropriate equivalence of sodium hydroxide and controlled reaction time. Febuxostat, on acetone recrystallization and seed Crystal A at 45°C, gave pure febuxostat with 75% yield.


  1. international names for febuxostat Page accessed June 25, 2015
  2.  Febuxostat for the management of hyperuricaemia in people with gout (TA164) Chapter 4. Consideration of the evidence
  3.  Uloric label Updated February, 2009.
  4.  Love BL, Barrons R, Veverka A, Snider KM (2010). “Urate-lowering therapy for gout: focus on febuxostat”. Pharmacotherapy 30 (6): 594–608. doi:10.1592/phco.30.6.594.PMID 20500048.
  5.  Ashraf Mozayani; Lionel Raymon (2011). Handbook of Drug Interactions: A Clinical and Forensic Guide. Springer Science+Business Media.
  6. Teijin Febuxostat Story Page accessed June 25, 2015
  7.  Tomlinson B. Febuxostat (Teijin/Ipsen/TAP). Curr Opin Investig Drugs. 2005 Nov;6(11):1168-78. PMID 16312139
  8.  Bruce Japsen for the Chicago Tribune. August 17, 2006. FDA puts gout treatment on hold
  9.  Note: TAP Pharmaceuticals was a joint venture between Abbott Laboratories and Takedathat was dissolved in 2008 per this press release: Takeda, Abbott Announce Plans to Conclude TAP Joint Venture
  10.  “Adenuric (febuxostat) receives marketing authorisation in the European Union” (PDF). Retrieved 2008-05-28.
  11.  “Uloric Approved for Gout”. U.S. News and World Report. Retrieved 2009-02-16.
  12.  Teijin and Takeda. February 14, 2009 Press release: ULORIC® (TMX-67, febuxostat) Receives FDA Approval for the Chronic Management of Hyperuricemia in Patients with Gout
  13.  Teijin. January 21, 2011 Press release: TMX-67 (febuxostat) Approved in Japan
  14.  Genetic Engineering News. October 2009. Menarini to Market Takeda/Ipsen Gout Therapy in 41 European Countries
  15.  First Word Pharma. April 1st, 2010 Teijin Pharma and Astellas Pharma enter into agreement for marketing rights of TMX-67 in China and Hong Kong
  16.  Research Views. Aug 11 2011 Teijin Pharma Enters Into Distribution Agreement With Astellas Pharma For Febuxostat

Febuxostat is an inhibitor of xanthine oxidase, and was developed by Teijin pharma. This compound is known as a new drug that is effective against gout and hyperuricemia, and it has been 40 years since the last time a drug of this kind of drug was developed.

Febuxostat has therefore gained a lot of popularity and it has already been accepted as a drug in Europe, USA, Korea and Japan. The synthesis of this molecule have been reported in patents by Teijin pharma as shown below.[1,2]


Recently, Itami group was reported the rapoid synthesis of febxostat by using Ni-catalyzed direct coupling of azoles and arylhalides[3]


Sorbera, L.A.; Castaner, J.; Rabasseda, X.; Revel, L.; TMX-67. Drugs Fut 2001, 26, 1, 32

[1] Hasegawa, M.; A facile one-pot synthesis of 4-alkoxy-1,3-benzenedicarbonitrile. Heterocycles 1998, 47, 2, 857. [2] Hasegawa, M.;  Hasegawa, M.; Komoriya, K. (Teijin Ltd.); Cyano cpds. and their preparation method. JP 1994345724 . [3] “Nickel-Catalyzed Biaryl Coupling of Heteroarenes and Aryl Halides/Triflates”

Canivet, J.; Yamaguchi, J.; Ban, I.; Itami, K. Org. Lett. 2009, 11, 1733-1736. DOI: 10.1021/ol9001587


Ni-based catalytic systems for the arylation of heteroarenes with aryl halides and triflates have been established. Ni(OAc)2/bipy is a general catalyst for aryl bromides/iodides, and Ni(OAc)2/dppf is effective for aryl chlorides/triflates. Thiazole, benzothiazole, oxazole, benzoxazole, and benzimidazole are applicable as heteroarene coupling partners. A rapid synthesis of febuxostat, a drug for gout and hyperuricemia, is also demonstrated.


A final example of a thiazole containing drug is given in the novel xanthine oxidase inhibitor febuxostat (359, Uloric) which was approved by the FDA in 2009. This inhibitor works by blocking xanthine oxidase in a non-competitive fashion. Consequently, the amount of the oxidation product uric acid is reduced. Thus it is an efficient treatment for hyperuricemia in gout. In order to prepare febuxostat first a synthesis of the noncommercial 4-isobutoxy-1,3-dicyanobenzene building block (363), has to be conducted. An elegant way of achieving this was shown through the reaction of 4-nitrocyanobenzene (360) with potassium cyanide in dry DMSO followed by quenching with isobutyl bromide under basic conditions (Scheme 70). It is suggested that a Meisenheimer-complex intermediate 361 is initially formed, which after rearomatisation, undergoes nucleophilic aromatic substitution of the nitro group by the DMSO solvent [107]. Upon hydrolysis and O-alkylation the desired 4-isobutoxy-1,3-dicyanobenzene (363) is obtained in good overall yield. Subsequently, the less hindered nitrile is converted to the corresponding thioamide 365 in an intriguing reaction using thioacetamide (364). The thiazole ring is then formed by condensation with chloroacetoacetate 366 followed by ester hydrolysis (Scheme 70).


107 Hasegawa, M. Heterocycles 1998, 47, 857–864. doi:10.3987/COM-97-S(N)89

Paper | Special issue | Vol 47, No. 2, 1998, pp.857-864

DOI: 10.3987/COM-97-S(N)89
A Facile One-Pot Synthesis of 4-Alkoxy-1,3-benzenedicarbonitrile

Masaichi Hasegawa

*Teijin Institute, Bio-Medical Research, Asahigaoka 4-3-2, Hino, Tokyo 191, Japan


2-(3-Cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxlic acid (TEI-6720) was prepared. The introduction of cyano group to 4-nitrobenzonitrile with KCN in dry DMSO followed by quenching with alkyl halide afforded the key intermediates, 4-alkoky-1,3-benzenedicarbonitriles, in good yield. The reaction was completed in dry DMSO, while no reaction occurred in dry DMF. This observation can be suggested by the participation of DMSO in the reaction.

PDF (208KB)


Synthesis and characterization of process-related impurities of an anti-hyperuricemia drug-Febuxostat

Venkateswara Rao Vallu,$ Krunal Girishbhai Desai, Sandip Dhaya Patil, Rajendra Agarwal, Pratap Reddy Padi and Mahesh Reddy Ghanta

*Process Research Laboratory-I, Research & Development Centre, Macleods Pharmaceuticals Ltd, G-2, Mahakali Caves Road, Shantinagar, Andheri (East), Mumbai, Maharastra, India

$Department of Chemistry, Pacific University, Pacific Hills, Airport Road, Pratap Nagar Extension, Debari, Udaipur, Rajasthan, India _____________________________________________________________________

Der Pharma Chemica, 2014, 6(3):300-311 (

Synthesis of 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid (1) [10] A solution of 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid (1 tech grade, 5.0 g, 0.015 mol.) in methanol (50.0 mL) was heated the reaction mass at 60-65°C till clear solution was obtained. Water (50.0 mL) was added drop wise into reaction mass with in 30.0 min. at 60-65°C. Resultant white crystalline solid was filtrated, Mahesh Reddy Ghanta et al Der Pharma Chemica, 2014, 6 (3):300-311 _____________________________________________________________________________ 302 washed with water (10.0 mL) and dried in vacuum tray drier at 50-55°C under vacuum to give

2-(3-cyano-4- isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid (1). Yield: 95.0 % (4.75 g)

mp 239°C. Purity by HPLC: 99.74 % (10.2 min. retention time),

Anal. Calcd for C16H16N2O3S: C, 60.74; H, 5.10; N, 8.85. Found: C, 60.70; H, 5.11; N, 8.87 %;

IR (KBr) υmax (in cm−1): 3834.61, 3742.03, 3680.30, 3556.85, 3456.55, 2962.76, 2877.89, 2661.85, 2546.12, 2353.23, 2229.79, 2168.06, 2029.18, 1921.16, 1790.00, 1674.27, 1604.83, 1512.24, 1427.37, 1381.08, 1280.78, 1172.76, 1118.75, 1010.73, 918.15, 833.28, 771.55, 725.26, 648.10, 524.66, 462.93; 1H NMR (300 MHz, CDCl3 or DMSO-d6) δH (in ppm): 1.00-1.02 (d, 6H, (CH3)2-CH-), 2.49-2.50 (m, 1H, (CH3)2-CH-), 3.97-3.99 (d, 2H, -CH-CH2−), 7.33–8.25 (d, dd, 3H, Ar-H), 2.64 (s, 3H, -CH3), 13.39 (s, 1H, -COOH);

13C NMR (300 MHz, DMSO–d6) δC (in ppm) (Positiona ): 166.3 (l), 162.9 (p), 162.2 (n), 159.6 (e), 133.1 (g), 131.6 (i), 125.5 (m), 123.0 (h), 115.5 (k), 114.0 (f), 101.7 (j), 75.2 (d), 27.7 (b), 18.8 (a, c), 17.1 (o);

MS m/z (%) (70 eV): m/z =317.0 (100.0 %) [M+1], 318.0 (16.0 %) [M+2], 403.0 (63.0 %), 512.0 (47.0 %), 482.0 (46.0 %), 405.0 (27.0 %), 468.0 (25.0 %), 570.0 (24.0 %).



WO 2012066561

As per the present invention, hydroxylamine hydrochloride is added to compound of Formula-Ill in presence of a polar aprotic solvent like DMSO, DMA, ACN or DMF. To this reaction mixture acetyl halides or sulfonyl chlorides are added and temperature raised to 70 -80 °C. Acetyl halides are selected from acetyl bromide or acetyl chloride. Sulfonyl chlorides are selected from methane sulfonyl chloride or para toluene sulfonyl chloride. To this reaction mixture a base selected from alkali metal carbonates like potassium carbonate or sodium carbonate, preferably potassium carbonate and alkyl halide selected from isobutyl bromide is successively added. The reaction mass is washed with water and compound of Formula-II is isolated. In one embodiment the present invention provides, process for the preparation of Febuxostat comprising the steps of:

a) reacting the compound of Formula-III(a) with hydroxylamine hydrochloride in presence of organic solvent;

Figure imgf000008_0001


b) adding acyl halides or sulfonyl chlorides to the reaction mixture;

c) optionally isolating compound of Formula- IV (a)

Figure imgf000008_0002


d) reacting with isobutyl bromide in presence of base;

e) isolating the compound of Formula-II(a); and

Figure imgf000008_0003


f) hydrolyzing the compound of Formula-II(a) to get Febuxostat.

The following examples are provided to illustrate the process of the present invention. They, are however, not intended to limiting the scope of the present invention in any way and several variants of these examples would be evident to person ordinarily skilled in the art. Experimental procedure:

Example – 1: Preparation of Ethyl-2-(3-cyano-4-isobutoxy phenyl)-4-methyI thiozole -5-carboxylate

A mixture of 10. Og of Ethyl -2-(3-formyl-4-hydroxy phenyl)-4-methyl thiozole -5- carboxylate and 2.85 g of hydroxylamine hydrochloride were stirred for 30 minutes in 40 g of Dimethyl sulfoxide. To this reaction mixture 3.3 grams of acetyl chloride was added and stirred at 70 -80°C for 2-3 hours. Reaction mass was cooled to room temperature and to this 19 g of potassium carbonate and 19 g of isobutyl bromide was added successively. The reaction mass was stirred for 5 hours at 70-80°C. Reaction mass was diluted with 200 ml of purified water. The reaction mass was filtered and washed with purified water to give 10.0 g of Ethyl-2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxyltae (yield 84.0%)

Example – 2: Preparation of Ethyl-2-(3-cyano-4-hydroxyphenyl)-4-methyl thiozole – 5-carboxylate

A mixture of 10. Og of Ethyl-2-(3-formyl-4-hydroxy phenyl)-4-methyl thiozole -5- carboxylate and 2.85 g of hydroxylamine hydrochloride were stirred for 30 minutes in 30 g of Dimethylformamide. To this reaction mixture 3.3 grams of acetyl chloride was added and stirred at 90°C for 2-3 hours. Reaction mass was cooled to room temperature and diluted with 100 ml of water and stir for 2 hours. The reaction mass was filtered and washed with purified water to give 10.0 g of Ethyl-2-(3-cyano-4-hydroxy phenyl)-4- methyl thiozole -5-carboxyltae (yield 99.0%).

Example – 3: Preparation of Ethyl 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylate

A mixture of 10. Og of Ethyl-2-(3-cyano-4-hydroxy phenyl)-4-methyl thiozole -5- carboxylate, 30 g of NMP, 9.6 g of potassium carbonate and 7.2 g of isobutyl bromide were stirred for 3 hours at 90°C. Reaction mass was diluted with 100 ml of purified water. The reaction mass was filtered and washed with purified water and ethanol to give 10.5 g of Ethyl-2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxyltae (yield 88.0%). Example – 4: Preparation of 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5- carboxylic acid

A mixture of 10. Og of Ethyl-2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5- carboxyltae, 2.0g of sodium hydroxide was heated at 45-60°C in 75 ml of aqueous methanol for 1 hour. Reaction mass was cooled to ambient temperature and pH adjusted to 2.0 to 2.5 with dilute hydrochloric acid and precipitated crystal was collected by filtration to give 8.8g of 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylic acid (yield 95.8%).

Example – 5-13: Preparation of 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole – 5-carboxylic acid

The above compound was prepared by following the procedure as disclosed in Example- 4, using the below listed solvents instead of aqueous methanol.

Figure imgf000010_0001

Example – 14: Preparation of pure 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylic acid

10.0 g of 2-(3-cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylic acid was dissolved in 100 ml of ethanol at reflux temperature. After dissolution reaction mass was cooled and precipitated crystal was collected by filtration to give 9.6 g of pure 2-(3- cyano-4-isobutoxy phenyl)-4-methyl thiozole -5-carboxylic acid (yield 96%).


KR 201603732


WO 2015018507


of compound of formula lib

Dissolve 14.14g of ethyl 2-(3-formyl-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate (Formula III) in 55 ml dimethylformamide, at ambient temperature. Add 40g of potassium carbonate, along with 15.9 ml isobutyl bromide. Heat the reaction to 75-80 °C and stir for 4 hours. Cool to 25-30 °C, while 165 ml process water is added. Further cool to 0-5 °C and stir for 30 minutes at this temperature. Filter off the precipitated solid and wash the filter cake with 55 ml process water. The wet cake is dried under vacuum at 40 °C for 7 hours, to furnish 16.43 g of ethyl 2-(3-formyl-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate (Formula lib).

of compound of formula Illb

In a 25 mL round-bottomed flask charge under stirring at 25-30 °C, 1.0 g (2.88 mmol) of ethyl 2-(3-formyl-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate in 3.0 mL dimethylformamide. Add 34 mg (0.19 mmol) copper acetate under stirring at 25-30 °C. Flush with oxygen (02) and add 0.66 ml (34.92 mmol) 25% aqueous ammonia. Flush again with 02. Heat the reaction mixture to 80-82 °C overnight. Check the progress of the reaction by TLC (cyclohexanerethyl acetate 3:1). Cool reaction mass to 25-30 °C. Add 25mL ethyl acetate and 25mL brine at the reaction mass, separate organic layer and extract aqueous layer twice with 25mL ethyl acetate. Combine organic layers, dry over anhydrous sodium sulfate, filter off and concentrate till dry. The residue is purified with column chromatography (cyclohexane:ethyl acetate 9:1). afforded 0.754g of ethyl 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate (Formula Illb) Yield: 75.4%.

EXAMPLE 3: Preparation of compound of formula Illb

In a 25 mL round-bottomed flask charge under stirring at 25-30 °C, 0.17 g (0.49 mmol) of ethyl 2-(3-formyl-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate in 2.5 mL tetrahydrofuran. Add 2.9 mL (153.43 mmol) 25% aqueous ammonia, under stirring at 25-30 °C. Add 137 mg (0.54 mmol) iodine (I2) to the reaction mass, stir the reaction mixture at 25-30 °C for 15-30 min. Check the progress of the reaction by TLC (cyclohexane: ethyl acetate 3:1). Starting material is consumed. Add 2.5 mL 5% w/v aqueous sodium thiosulfate Na2S203 and 15mL ethyl acetate at the reaction mass, separate organic layer and extract twice aqueous layer with 15mL ethyl acetate. Combine organic layers, dry over anhydrous sodium sulfate, filter off and concentrate till dry. 0.158g of ethyl 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate (Formula Illb) are collected.

EXAMPLE 4: Preparation of Febuxostat

In a 100 ml 2-neck round-bottomed flask charge 2.407g of ethyl-2-(3-cyano-4-isobutoxyphenyl)-4-methylhiazole-carboxylate in 20ml tetrahydrofuran under stirring, at 25-35 °C, 0.748g of sodium hydroxide and heat reaction mass to 60-65 °C for approximately 8 hrs. Check the progress of the reaction by TLC (cyclohexane:ethyl acetate 3:1). Cool reaction mass to 0-5 °C and add 50 ml process water keeping temperature within 0-5 °C. Adjust pH to 1-2 with 4.5 ml 6 N hydrochloric acid, keeping temperature within 0-5 °C. Warm up reaction mass to 25-30 °C and stir reaction mass at the above temperature for 15 min. Filter off the precipitated solid through Buchner funnel under reduced pressure, spray wash with 2 ml process water and suck dry for 20-30 min. Transfer the crude solid in a 50 ml round-bottomed flask, charge 12 ml process water and 12 ml acetone at 25-30°C. Heat the reaction mass to 50-60 °C for 60 min. Cool down reaction mass to 0-5 °C and stir for 60 min at the above temperature. Filter off the precipitated solid though Buchner funnel under reduced pressure, spray wash with 2 ml of a 1 : 1 mixture of acetone and process water and suck dry for 30-45 min. Dry under vacuum at 60 °C. 1.821g of (compound I) Febuxostat are collected, Purity: 82.6%, Yield: 0.62w/w.

on of compound of formula Ilia

In a 50 mL round-bottomed flask charge under stirring 0.5g (1.72 mmol) of ethyl 2-(3-formyl-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate in 8.6 mL THF, at 25-30 °C. Add 10.3 mL (544.94 mmol) 25% aqueous ammonia, under stirring at 25-30 °C. Add 480 mg (1.89 mmol) iodine (I2) to the reaction mass, stir the reaction mixture at 25-30 °C for 15-30 min. Check the progress of the reaction by TLC (cyclohexane: ethyl acetate 1 :1). Starting material is consumed. Add 8.6 mL 5% w/v aqueous thiosulfate and 40 mL ethyl acetate at the reaction mass, separate organic layer and extract aqueous layer twice with 40 mL ethyl acetate. Combine organic layers, dry over anhydrous sodium sulfate, filter off and concentrate to dryness. Purification of the residue with column chromatography (cyclohexane: ethyl acetate 3: 1) afforded 0.213 g of ethyl 2-(3-cyano-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate (Formula Ilia). Yield : 42.6%.

EXAMPLE 6: Preparation of compound Illb

Dissolve 2.2 g of ethyl 2-(3-cyano-4-hydroxyphenyl)-4-methylthiazole-5-carboxylate (Formula VI) in 7 ml dimethylformamide and to this mixture add 6.6 g of potassium carbonate and 3.14 g of isobutyl bromide. Stir the reaction at 75 °C for 15 hours and then cool to 40 °C. Add 15 ml process water and cool to 0-5 °C. Filter the precipitated solid off and wash with 15 ml process water, which, after drying, affords 2.28 g of ethyl 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylate (Formula Illb).

EXAMPLE 7: Preparation of compound I (Febuxostat)

In a 100 ml 2-neck round-bottomed flask charge 2.131 g of ethyl-2(3-cyano-4-isobutoxyphenyl)-4-methylhiazole-carboxylate, 64 ml methanol and 2.5 ml process water are added under stirring at 25-35 °C. Add 1.718 g potassium carbonate and heat reaction mass to reflux for approximately 2-3 hrs. Check the progress of the reaction by TLC (cyclohexane: ethyl acetate 3:1). Cool reaction mass to 20-25 °C. Concentrate solvent at below 40 °C. To the residue add 43 ml process water, 21 ml ethyl acetate and stir for 30 min at 25-35 °C. Separate layers and transfer aqueous layer in a 100 ml round-bottomed flask. Adjust pH to 2.3-2.7 with 25 ml 1 N hydrochloric acid, at 25-35 °C. Warm up reaction mass to 40 °C and stir reaction mass at this temperature for 60-90 min. Cool down reaction mass to 25-35 °C. Filter off the precipitated solid through Buchner funnel under reduced pressure, spray wash with 5 ml process water and suck dry for 30-45 min. Dry under vacuum at 60 °C. 1.708g of (compound I) Febuxostat are collected, Purity: 86.7%, Yield: 0.69w/w.

EXAMPLE 8: Preparation of Febuxostat crystalline form III

In a 250 mL round-bottomedflask charge under stirring at 25-30 °C 10 g of crude 2-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-5-carboxylic acid (Febuxostat) in 200 mL ethyl acetate. Heat reaction mass to reflux and stir for 30 min. Cool reaction mass to 25-30°C. Warm again reaction mass and partially distill off solvent from the reaction mass at temperature below 40 °C under reduced pressure. Cool reaction mass to 25-30°C. Filter off the precipitated solid through Buchner funnel under reduced pressure and spray wash with 10 mL ethyl acetate. Dry under vacuum at 60°C. 8.5 g of Febuxostat are collected. Yield: 85 % w/w. XRPD of crystalline compound is in accordance with the one reported in Chinese patent CN101412700B.


CN 104418823

Figure CN104418823AD00042


CN 103588723

Chinese patent CN1275126 described by the Japanese company Teijin invention relates febuxostat Form A, B, C, D, G, and six kinds of amorphous and crystalline preparation method, reported in the literature Form A relatively stable . The method used is a solvent of methanol and water, patent phase diagram (Figure 7 Zone I) can be obtained in anhydrous crystalline Form A (hereinafter referred to as “Form A”), the mixing process by a temperature and the formation of methanol and water to determine the composition of the solvent, and the need to add a certain amount of Form a as a seed crystal to induce precipitation of crystals to control crystallization conditions are very harsh, operable range is very small, easy to form methanol solvate, hydrate or stable crystalline type C, to obtain reproducible single crystal type a low, it is difficult to achieve industrial production, and no mention of the preparation of Form a yield and purity in this patent.


[0012] Chinese patent CN102267957A invention discloses a method for preparing febuxostat Form A, the solvent is preferably acetone, dissolved into 25 ~ 40 ° C was allowed to stand, when there began to crystallize when stirred for 20 to 40 minutes, then placed in -15 ~ 0 ° C to continue the crystallization of 8 to 10 hours. The crystallization process need to well below zero, when industrial mass production, resulting in high production costs, is not conducive to industrial production, the process yield up to 95.4%.

[0013] Chinese patent CN101139325 of Example 7 discloses the preparation of Form A with acetone method, although the process is simple, but the yield is low, only 50%.

[0014] Although the Chinese patent CN101684108A isopropyl alcohol as a solvent is disclosed a method for preparing crystalline form, the crystalline form of preparation is used to cool and heat a phased manner was allowed to stand, the crystallization temperature, long crystallization time, about 30 hours, the yield is low, and its products are not crystalline Form A.

[0015] In addition, Chinese patent CN101525319A, CN101805310, CN101926795A, CN101926794, W02012020272A2 are disclosed ethanol as a solvent or aqueous ethanol as a solvent preparation methods, and its products are crystalline ethanol solvate.

[0016] World Patent W02011139886A2 discloses the use of a mixed solvent of alcohol, and its products are not obtained polymorph A0


Letters in Organic Chemistry (2015), 12(3), 217-221

Synthesis of the Major Metabolites of Febuxostat

Author(s): Xiao Long Li, Rui Qiu, Wei Li Wan, Xu Cheng, Li Hai and Yong Wu

Affiliation: Key Laboratory of Drug Targeting of Education Ministry, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.

Graphical Abstract:


Total synthesis of three Febuxostat metabolites, named 67M-1, 67M-2, and 67M-4,is described in this article. Through condensation of the key intermediate compound A with different side chains, and then oxidation and hydrolysis, we obtained three target compounds with an overall yield of 19.5%-28.0%.

Page: [217 – 221]
Pages: 5
DOI: 10.2174/1570178612666150108000805

ULORIC (febuxostat) is a xanthine oxidase inhibitor. The active ingredient in ULORIC is 2-[3-cyano-4-(2-methylpropoxy) phenyl]-4-methylthiazole-5-carboxylic acid, with a molecular weight of 316.38. The empirical formula is C16H16N2O3S.

The chemical structure is:


ULORIC (febuxostat) Structural Formula Illustration

Febuxostat is a non-hygroscopic, white crystalline powder that is freely soluble in dimethylformamide; soluble in dimethylsulfoxide; sparingly soluble in ethanol; slightly soluble in methanol and acetonitrile; and practically insoluble in water. The melting range is 205°C to 208°C.

LORIC tablets for oral use contain the active ingredient, febuxostat, and are available in two dosage strengths, 40 mg and 80 mg. Inactive ingredients include lactose monohydrate, microcrystalline cellulose, hydroxypropyl cellulose, sodium croscarmellose, silicon dioxide and magnesium stearate. ULORIC tablets are coated with Opadry II, green.

CN1642546A * Mar 28, 2003 Jul 20, 2005 Teijin Ltd. Containing a single crystalline solid preparation
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WO2015018507A3 * Jul 30, 2014 Oct 22, 2015 Pharmathen S.A. A novel process for the preparation of febuxostat
CN103304512A * Jun 4, 2013 Sep 18, 2013 华南理工大学 Preparation method for febuxostat
WO2011031409A1 * Aug 12, 2010 Mar 17, 2011 Teva Pharmaceutical Industries Ltd. Processes for preparing febuxostat
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CN101863854A * Jun 29, 2010 Oct 20, 2010 沈阳药科大学 Synthesis method of 2-(3-cyan-4-isobutoxy) phenyl-4-methyl-5-thiazole formic acid
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1 * HASEGAWA, M. ET AL.: ‘A facile one-pot synthesis of 4-alkoxy-1,3-benzenedicarbonitrile‘ HETEROCYCLES vol. 47, no. 2, 1998, pages 857 – 864
Citing Patent Filing date Publication date Applicant Title
WO2012131590A1 * Mar 28, 2012 Oct 4, 2012 Sandoz Ag An improved process for preparation of febuxostat and its polymorphic crystalline form c thereof
WO2014009817A1 * Mar 19, 2013 Jan 16, 2014 Alembic Pharmaceuticals Limited Pharmaceutical composition of febuxostat
WO2014057461A1 Oct 10, 2013 Apr 17, 2014 Ranbaxy Laboratories Limited Process for the preparation of crystalline form g of febuxostat
Systematic (IUPAC) name
1,3-thiazole-5-carboxylic acid
Clinical data
Trade names Uloric, Adenuric, Atenurix, Feburic, Goturic, Goutex. Generic in several countries.[1]
AHFS/ Monograph
MedlinePlus a609020
License data
  • US: C (Risk not ruled out)
Routes of
Legal status
Legal status
Pharmacokinetic data
Bioavailability ~49% absorbed
Protein binding ~99% to albumin
Metabolism via CYP1A2, 2C8, 2C9,UGT1A1, 1A3, 1A9, 2B7
Biological half-life ~5-8 hours
Excretion Urine (~49% mostly as metabolites, 3% as unchanged drug); feces (~45% mostly as metabolites, 12% as unchanged drug)
CAS Number 144060-53-7 
ATC code M04AA03 (WHO)
PubChem CID 134018
DrugBank DB04854 Yes
ChemSpider 118173 Yes
UNII 101V0R1N2E Yes
KEGG D01206 Yes
ChEMBL CHEMBL1164729 Yes
Chemical data
Formula C16H16N2O3S
Molar mass 316.374 g/mol

/////////Febuxostat, 144060-53-7, Uloric, Adenuric,  Tei 6720,  thiazole derivative, inhibitor of XANTHINE OXIDASE,  treatment of HYPERURICEMIA, chronic GOUT, FBX, Febugood, Feburic, Febutaz, TMX 67, Zurig





Rifaxidin; Rifacol; Xifaxan; Normix; Rifamycin L 105;L 105 (ansamacrolide antibiotic), L 105SV


 CAS 80621-81-4,  4-Deoxy-4-methylpyrido[1,2-1,2]imidazo[5,4-c]rifamycin SV,

4-Deoxy-4′-methylpyrido[1′,2′-1,2]imidazo[5,4-c]rifamycin SV, Rifacol

Molecular Weight: 785.87854 g/mol

XIFAXAN tablets for oral administration are film-coated and contain 200 mg or 550 mg of rifaximin.

Rifaximin is an orally administered, semi-synthetic, nonsystemic antibiotic derived from rifamycin SV with antibacterial activity. Rifaximin binds to the beta-subunit of bacterial DNA-dependent RNA polymerase, inhibiting bacterial RNA synthesis and bacterial cell growth. As rifaximin is not well absorbed, its antibacterial activity is largely localized to the gastrointestinal tract.

Rifaximin (trade names:RCIFAX, Rifagut, Xifaxan, Zaxine) is a semisynthetic antibiotic based on rifamycin. It has poor oral bioavailability, meaning that very little of the drug will be absorbed into the blood stream when it is taken orally. Rifaximin is used in the treatment of traveler’s diarrhea, irritable bowel syndrome, and hepatic encephalopathy, for which it receivedorphan drug status from the U.S. Food and Drug Administration in 1998.

 Rifaximin is a rifamycin that was launched in 1988 by Alfa Wasserman for the treatment of bacterial infection, and was commercialized in 2004 by Salix for the treatment of Clostridium difficile-associated diarrhea. In 2008, the product was launched in Germany for the treatment of travelers’ diarrhea caused by non-invasive enteropathogenic bacteria in adults. In 2015, Xifaxan was approved in the U.S. for the treatment of abdominal pain and diarrhea in adult men and women with irritable bowel syndrome with diarrhea. At the same year, Aska filed an application for approval of the product in Japan for the treatment of hepatic encephalopathy.

Rifaximin is licensed by the U.S. Food and Drug Administration to treat traveler’s diarrhea caused by E. coli.[1] Clinical trials have shown that rifaximin is highly effective at preventing and treating traveler’s diarrhea among travelers to Mexico, with fewside effects and low risk of developing antibiotic resistance.[2][3][4] It is not effective against Campylobacter jejuni, and there is no evidence of efficacy against Shigella or Salmonella species.

Launched – 1988 Alfa Wassermann Infection, bacterial
Launched – 2004 Salix Traveler’s diarrhea
Launched – 2010 Salix Encephalopathy, hepatic
Launched – 2015 Salix Irritable bowel syndrome (Diarrhea predominant)
Launched Alfa Wassermann
Merck & Co.

The drug is also at Salix in phase II trials for the treatment of Crohn’s disease. Alfa Wasserman is also conducting phase II trials for Crohn’s disease. The product was approved and launched in the U.S. for the maintenance of remission of hepatic encephalopathy in 2010. Mayo Clinic is conducting phase II clinical trials in the U.S. for the treatment of primary sclerosing cholangitis and the University of Hong Kong is also conducting Phase II trials for the treatment of functional dyspepsia.

It may be efficacious in relieving chronic functional symptoms of bloating and flatulence that are common in irritable bowel syndrome (IBS),[5][6] especially IBS-D.

In February 1998, Salix was granted orphan drug designation by the FDA for the use of rifaximin to treat hepatic encephalopathy. In 2009, a codevelopment agreement was established between Lupin and Salix in the U.S. for the development of a new formulation using Lupin’s bioadhesive drug delivery technology.

There was recentlya pilot-study done on the efficacy of rifaximin as a means of treatment for rosacea, according to the study, induced by the co-presence of small intestinal bacterial overgrowth.[7]

In the United States, rifaximin has orphan drug status for the treatment of hepatic encephalopathy.[8] Although high-quality evidence is still lacking, rifaximin appears to be as effective as or more effective than other available treatments for hepatic encephalopathy (such as lactulose), is better tolerated, and may work faster.[9] Hepatic encephalopathy is a debilitating condition for those with liver disease. Rifaximin is an oral medication taken twice daily that helps patients to avoid reoccurring hepatic encephalopathy. It has minimal side effects, prevents reoccurring encephalopathy and high patient satisfaction. Patients are more compliant and satisfied to take this medication than any other due to minimal side effects, prolong remission, and overall cost.[10] Rifaximin helps patients avoid multiple readmissions from hospitals along with less time missed from work as well. Rifaximin should be considered a standard prescribed medication for those whom have episodes of hepatic encephalopathy.

The drawbacks to rifaximin are increased cost and lack of robust clinical trials for HE without combination lactulose therapy.

Also treats hyperammonemia by eradicating ammoniagenic bacteria.

Mechanism of action

Rifaximin interferes with transcription by binding to the β-subunit of bacterial RNA polymerase.[11] This results in the blockage of the translocation step that normally follows the formation of the first phosphodiester bond, which occurs in the transcription process.[12]


A 2011 study in patients with IBS (sans constipation) indicated 11% showed benefits over a placebo.[13] The study was supported by Salix Pharmaceuticals, the patent holder.[13] A 2010 study in patients treated for Hepatic Cirrhosis with hospitalization involving Hepatic encephalopathy resulted in 22% of the rifaxmin treated group experiencing a breakthrough episode of Hepatic encephalopathy as compared to 46% of the placebo group. The majority patients were also receivingLactulose therapy for prevention of hepatic encephalopathy in addition to Rifaximin.[14] Rifaximin shows promising results, causing remission in up to 59% of people with Crohn’s disease and up to 76% of people with Ulcerative Colitis.[15]


In the United States, Salix Pharmaceuticals holds a US Patent for rifaximin and markets the drug under the name Xifaxan, available in tablets of 200 mg and 550 mg.[16][17] In addition to receiving FDA approval for traveler’s diarrhea and (marketing approved for)[17] hepatic encephalopathy, Xifaxan received FDA approval for IBS in May 2015.[18] No generic formulation is available in the US and none has appeared due to the fact that the FDA approval process was ongoing. If Xifaxan receives full FDA approval for hepatic encephalopathy it is likely that Salix will maintain marketing exclusivity and be protected from generic formulations until March 24, 2017.[17] Price quotes received on February 21, 2013 for Xifaxan 550 mg in the Denver Metro area were between $23.57 and $26.72 per tablet. A price quote received on June 24, 2016 for Xifaxan 550 mg was $31.37 per tablet.

Rifaximin is approved in 33 countries for GI disorders.[19][20] On August 13, 2013, Health Canada issued a Notice of Compliance to Salix Pharmaceuticals Inc. for the drug product Zaxine.[21] In India it is available under the brand names Ciboz and Xifapill.[










Direct infusion mass analysis ESI (+)







Rifaximin is a broad-spectrum antibiotic belonging to the family of Rifamycins and shows its antibacterial activity, in the gastrointestinal tract against localized bacteria that cause infectious diarrhoea, irritable bowel syndrome, small intestinal bacterial overgrowth, Crohn’s disease, and/or pancreatic insufficiency.

Rifaximin is sold under the brand name Xifaxan® in US for the treatment of Travellers’ diarrhoea and Hepatic Encephalopathy. The chemical name of Rifaximin is (2S , 16Z, 18E,20S ,21 S ,22R,23R,24R,25S ,26S ,27S ,28E)-5,6,21 ,23 ,25-pentahydroxy-27-methoxy-2,4,1 l,16,20,22,24,26-octamethyl-2,7(epoxypentadeca-[l,l l,13]trienimino) benzofuro[4,5-e]pyrido[l,2-a]-benzimidazole-l,15(2H)-dione,25-acetate and the molecular formula is G^HsiNsOn with a molecular weight of 785.9. The structural formula of Rifaximin is:

Formula I

Rifaximin was first described and claimed in Italian patent IT 1154655 and U.S. Pat. No.4,341,785. These patents disclose a process for the preparation of Rifaximin and a method for the crystallisation thereof. The process for the preparation of Rifaximin is as depicted in scheme I given below:

Scheme -I

U.S. Pat. No. 4,179,438 discloses a process for the preparation of 3-bromorifamycin S which comprises reaction of rifamycin S with at least two equivalents of bromine, per one mole of rifamycin S in the presence of at least one mole of pyridine per each equivalent of bromine and in the presence of ethanol, methanol or mixtures thereof with water at a

temperature not above the room temperature. The process is shown in the scheme given below:

Rifamycin S 3-Bromo-Rifamycin-S

U.S. Patent No.4,557, 866 discloses a process for one step synthesis of Rifaximin from Rifamycin O, which is shown in scheme II given below:

Rifamycin O                                                                                                               Rifaximin

Scheme -II

US ‘866 patent also discloses purification of Rifaximin by performing crystallization of crude Rifaximin from a 7:3 mixture of ethyl alcohol/water followed by drying both under atmospheric pressure and under vacuum. The crystalline form which is obtained has not been characterized.

U.S. Patent No. 7,045,620 describes three polymorphic forms α, β and γ of Rifaximin. Form a and β show pure crystalline characteristics while the γ form is poorly crystalline. These polymorphic forms are differentiated on the basis of water content and PXRD. This patent also discloses processes for preparation of these polymorphs which involve use of specific reaction conditions during crystallization like dissolving Rifaximin in ethyl alcohol at 45-65°C, precipitation by adding water to form a suspension, filtering suspension and washing the resulted solid with demineralized water, followed by drying at room temperature under vacuum for a period of time between 2 and 72 hours. Crystalline forms a and β are obtained by immediate filtration of suspension when temperature of reaction mixture is brought to 0°C and poorly crystalline form γ is obtained when the reaction mixture is stirred for 5-6 hours at 0°C and then filtered the suspension. In addition to above these forms are also characterized by specific water content. For a form water content should be lower than 4.5%, for β form it should be higher than 4.5% and to obtain γ form, water content should be below 2%.

U.S. Patent No. 7,709,634 describes an amorphous form of Rifaximin which is prepared by dissolving Rifaximin in solvents such as alkyl esters, alkanols and ketones and precipitating by addition of anti-solvents selected from hydrocarbons, ethers or mixtures thereof.

U.S. Patent No. 8,193,196 describes two polymorphic forms of Rifaximin, designated δ and ε respectively. Form δ has water content within the range from 2.5 to 6% by weight (preferably from 3 to 4.5%).

U.S. Patent No 8,067,429 describes a-dry, β-1, β-2, ε-dry and amorphous forms of Rifaximin.

U.S. Patent No. 8,227,482 describes polymorphs Form μ, Form π, Form Omicron, Form Zeta, Form Eta, Form Iota and Form Xi of Rifaximin.

International application publications WO 2008/035109, WO 2008/155728, WO 2012/035544, WO 2012/060675, and WO 2012/156533 describes various amorphous or poorly crystalline forms of Rifaximin.

These polymorphic forms are obtained under different experimental conditions and are characterized by XRPD pattern.

The polymorphic forms of Rifaximin obtained from the prior art methods have specific water content. Transition between different polymorphic forms of Rifaximin occurs by drying or wetting of the synthesized Rifaximin. Hence, it is evident from above that Rifaximin can exist in number of polymorphic forms, formation of these polymorphic forms depends upon specific reaction conditions applied during crystallization and drying.

Rifaximin is a semi-synthetic, rifamycin-based non-systematic antibiotic. It is chemically termed as (2S,16Z,18E,20S,21S,22R,23R,24R,25S,26 S,27S, 28E)-5,6,21,23,255-pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1,11,13]trienimino)benzofuro[4,5-e]pyrido[1,2-a]-benzimida-zole-1,15(2H)-dione,25-acetate (I).

Figure imgb0001

Rifaximin is used for treatment of travelers’ diarrhea caused by noninvasive strains of Escherichia coli.

Rifaximin was first disclosed in US4341785 which also discloses a process for its preparation and a method for crystallization of rifaximin using suitable solvents or mixture of solvents. However, this patent does not mention the polymorphism of rifaximin.

Canadian patent CA1215976 discloses a process for the synthesis of imidazo rifamycins which comprises reacting rifamycin S with 2-amino-4-methyl pyridine.

US4557866 discloses a process for preparation of rifaximin, but does not mention the polymorphs of rifaximin.

US7045620 discloses crystalline polymorphic forms of rifaximin which are termed as rifaximin α, rifaximin β and rifaximin γ. These polymorphic forms are characterized using X-ray powder diffraction. Further this patent mentions that γ form is poorly crystalline with a high content of amorphous component. This patent also discloses processes for preparation of these polymorphs which involve use of processes of crystallization and drying as disclosed in US4557866along with control of temperature at which the product is crystallized, drying process, water content thereof. Further, according to this patent, crystal formation depends upon the presence of water within the crystallization solvent.

The above patent discloses rifaximin α which is characterized by water content lower than 4.5% & powder X-ray diffractogram having significant peaks are at values of diffraction angles 2θ of 6.6°; 7.4°; 7.9°, 8.8°, 10.5°, 11.1 °, 11.8°, 12.9°, 17.6°, 18.5°, 19.7°, 21.0°, 21.4°, 22.1°; rifaximin β which is characterized by water content higher than 4.5% & powder X-ray diffractogram having significant peaks are at values of diffraction angles 2θ of 5.4°; 6.4°; 7.0°, 7.8°, 9.0°, 10.4°, 13.1°, 14.4°, 17.1°, 17.9°, 18.3°, 20.9° and rifaximin γ which is characterized by poorer powder X-ray diffractogram because of poor crystallinity. The significant peaks are at values of diffraction angles 2θ of 5.0°; 7.1°; 8.4°.

US2005/0272754 also discloses polymorphs of rifaximin namely rifaximin α form, rifaximin β form & rifaximin γ form characterized by powder X-ray diffractogram, intrinsic dissolution rates and processes of preparation of polymorphic forms of rifaximin. However, none of the above patents disclose a wholly amorphous form of rifaximin.

It is a well known fact that different polymorphic forms of the same drug may have substantial differences in certain pharmaceutically important properties. The amorphous form of a drug may exhibit different dissolution characteristics and in some case different bioavailability patterns compared to crystalline forms.

Further, amorphous and crystalline forms of a drug may have different handling properties, dissolution rates, solubility, and stability.

Furthermore, different physical forms may have different particle size, hardness and glass transition temperatures. Amorphous materials do not exhibit the three-dimensional long-range orders found in crystalline materials, but are structurally more similar to liquids where the arrangement of molecules is random.

Amorphous solids do not give a definitive x-ray diffraction pattern (XRD). In addition, amorphous solids do not give rise to a specific melting point and tend to liquefy at some point beyond the glass transition temperature. Because amorphous solids do not have lattice energy, they usually dissolve in a solvent more rapidly and consequently may provide enhanced bioavailability characteristics such as a higher rate and extent of absorption of the compound from the gastrointestinal tract. Also, amorphous forms of a drug may offer significant advantages over crystalline forms of the same drug in the manufacturing process of solid dosage form such as compressibility.


The schematic representation for preparation of amorphous rifaximin is as follows :

Figure imgb0002

Amorphous rifaximin according to the present invention can be characterized by various parameters like solubility, intrinsic dissolution, bulk density, tapped density.

Rifaximin is known to exist in 3 polymorphic Forms namely α Form, β Form & γ Form of which the α Form is thermodynamically the most stable. Hence, the amorphous form of rifaximin was studied in comparison with α Form.

Further, when intrinsic dissolution of amorphous rifaximin is carried out against the α Form, it is observed that the amorphous rifaximin has better dissolution profile than α Form which is shown in table below (this data is also shown graphically in Figure 3):

Dissolution medium : 1000 ml of 0.1M Sodium dihydrogen phosphate monohydrate + 4.5g of sodium lauryl sulphate

Temperature : 37±0.5°C

Rotation speed : 100 rpm

Particle size : Amorphous rifaximin – 11 microns

α Form of rifaximin – 13 microns

  • Time in minutes % Release of Amorphous Rifaximin % Release of α Form of Rifaximin
    15 1.1 0.8
    30 1.9 1.8
    45 2.9 3.0
    60 3.7 4.4
    120 8.1 11.0
    180 12.6 18.0
    240 16.6 24.6
    360 24.7 38.7
    480 32.0 47.5
    600 39.5 52.7
    720 46.4 56.4
    960 60.4 62.9
    1200 72.9 67.8
    1400 83.0 72.7
    Amorphous rifaximin exhibits bulk density in the range of 0.3 – 0.4 g/ml and tapped density is in the range of 0.4 – 0.5 g/ml while the α Form rifaximin exhibits bulk density in the range of 0.2 – 0.3 g/ml & tapped density is in the range of 0.3 – 0.4 g/ml. These higher densities of amorphous rifaximin are advantageous in formulation specifically in tablet formulation, for example, it gives better compressibility.


Rifaximin (CAS NO.: 80621-81-4), with other name of 4-Deoxy-4-methylpyrido[1,2-1,2]imidazo[5,4-c]rifamycin SV, could be produced through many synthetic methods.

Following is one of the reaction routes:

The reaction of rifamycin S (I) with pyridine perbromide (II) in 2-propanol/chloroform (70/30) mixture at 0 C gives 3-bromorifamicin S (III), which is then condensed with 2-amino-4-methyl-pyridine (IV) at 10 C. The o-quinoniminic compound (V) is then obtained. This compound is finally reduced with ascorbic acid.


Rifaximin (INN; see The Merck Index, XIII Ed., 8304) is an antibiotic belonging to the rifamycin class, exactly it is a pyrido-imidazo rifamycin described and claimed in Italian Patent IT 1154655, while European Patent EP 0161534 describes and claims a process for its production starting from rifamycin O (The Merck Index, XIII Ed., 8301).

Both these patents describe the purification of rifaximin in a generic way stating that crystallization can be carried out in suitable solvents or solvent systems and summarily showing in some examples that the reaction product can be crystallized from the 7:3 mixture of ethyl alcohol/water and can be dried both under atmospheric pressure and under vacuum without specifying in any way either the experimental conditions of crystallization and drying, or any distinctive crystallographic characteristic of the obtained product.

The presence of different polymorphs had just not been noticed and therefore the experimental conditions described in both patents had been developed with the goal to get a homogeneous product having a suitable purity from the chemical point of view, independent from the crystallographic aspects of the product itself.

It has now been found, unexpectedly, that there are several polymorphous forms whose formation, besides the solvent, depends on time and temperature conditions under which both crystallization and drying are carried out.

In the present application, these orderly polymorphous forms will be, later on, conventionally identified as rifaximin α (FIG. 1) and rifaximin β (FIG. 2) on the basis of their respective specific diffractograms, while the poorly crystalline form with a high content of amorphous component will be identified as rifaximin γ (FIG. 3).

Rifaximin polymorphous forms have been characterized through the technique of the powder X-ray diffraction.

The identification and characterization of these polymorphous forms and, simultaneously, the definition of the experimental conditions for obtaining them is very important for a compound endowed with pharmacological activity which, like rifaximin, is marketed as medicinal preparation, both for human and veterinary use. In fact it is known that the polymorphism of a compound that can be used as active ingredient contained in a medicinal preparation can influence the pharmaco-toxicologic properties of the drug. Different polymorphous forms of an active ingredient administered as drug under oral or topical form can modify many properties thereof like bioavailability, solubility, stability, colour, compressibility, flowability and workability with consequent modification of the profiles of toxicological safety, clinical effectiveness and productive efficiency.

What mentioned above is confirmed by the fact that the authorities that regulate the grant of marketing authorization of the drugs market require that the manufacturing methods of the active ingredients are standardized and controlled in such a way that they give homogeneous and sound results in terms of polymorphism of production batches (CPMP/QWP/96, 2003—Note for Guidance on Chemistry of new Active Substance; CPMP/ICH/367/96—Note for guidance specifications: test procedures and acceptance criteria for new drug substances and new drug products: chemical substances; Date for coming into operation: May 2000).

The need for the above-mentioned standardization has further been strengthened in the field of the rifamycin antibiotics by Henwood S. Q., de Villiers M. M., Liebenberg W. and Lotter A. P., Drug Development and Industrial Pharmacy, 26 (4), 403-408, (2000), who have ascertained that different production batches of the rifampicin (INN) made from different manufacturers differ from each other in that they show different polymorphous characteristics, and as a consequence they show different dissolution profiles, along with a consequent alteration of the respective pharmacological properties.

By applying the crystallization and drying processes generically disclosed in the previous patents IT 1154655 and EP 0161534 it has been found that under some experimental conditions a poorly crystalline form of rifaximin is obtained, while under other experimental conditions other polymorphic crystalline forms of Rifaximin are obtained. Moreover it has been found that some parameters, absolutely not disclosed in the above-mentioned patents, like for instance preservation conditions and the relative ambient humidity, have the surprising effect to determine the polymorph form.

The polymorphous forms of rifaximin object of the present patent application were never seen or hypothesized, while thinking that, whichever method was used within the range of the described condition, a sole homogeneous product would always have been obtained, irrespective of crystallizing, drying and preserving conditions. It has now been found that the formation of α, β and γ forms depends both on the presence of water within the crystallization solvent, on the temperature at which the product is crystallized and on the amount of water present in the product at the end of the drying phase. Form α, form β and form γ of rifaximin have then been synthesized and they are the object of the invention.

Moreover it has been found that the presence of water in rifaximin in the solid state is reversible, so that water absorption and/or release can take place in time in presence of suitable ambient conditions; consequently rifaximin is susceptible of transition from one form to another, also remaining in the solid state, without need to be again dissolved and crystallized. For instance polymorph α, getting water by hydration up to a content higher than 4.5%, turns into polymorph β, which in its turn, losing water by drying up to a content lower than 4.5%, turns into polymorph α.

These results have a remarkable importance as they determine the conditions of industrial manufacturing of some steps of working which could not be considered critical for the determination of the polymorphism of a product, like for instance the washing of a crystallized product, or the preservation conditions of the end product, or the characteristics of the container in which the product is preserved.

The above-mentioned α, β and γ forms can be advantageously used as pure and homogeneous products in the manufacture of medicinal preparations containing rifaximin.

As already said, the process for manufacturing rifaximin from rifamycin O disclosed and claimed in EP 0161534 is deficient from the point of view of the purification and identification of the product obtained; it shows some limits also from the synthetic point of view as regards, for instance, the very long reaction times, from 16 to 72 hours, not very suitable to an industrial use and moreover because it does not provide for the in situ reduction of rifaximin oxidized that may be formed within the reaction mixture.

Therefore, a further object of the present invention is an improved process for the industrial manufacturing of the α, β and γ forms of rifaximin, herein claimed as products and usable as defined and homogeneous active ingredients in the manufacture of the medicinal preparations containing such active ingredient.


FIG. 1 is a powder X-ray diffractogram of rifaximin polymorphic form α.

FIG. 2 is a powder X-ray diffractogram of rifaximin polymorphic form β.

FIG. 3 is a powder X-ray diffractogram of rifaximin polymorphic form γ.


Patent US20130004576

Rifaximin (INN; see The Merck Index, XIII Ed., 8304, CAS no. 80621-81-4), IUPAC nomenclature (2S,16Z,18E,20S,21S,22R,23R,24R,25S,26S,27S,28E)-5,6,21,23,25 pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-(1,11,13)trienimino)benzofuro(4,5-e)pyrido(1,2,-a)benzimidazole-1,15(2H)-dione,25-acetate) is a semi-synthetic antibiotic belonging to the rifamycin class of antibiotics. More precisely rifaximin is a pyrido-imidazo rifamycin described in the Italian patent IT 1154655, whereas the European patent EP 0161534 discloses a process for rifaximin production using rifamycin O as starting material (The Merck Index, XIII Ed., 8301).

U.S. Pat. No. 7,045,620, US 2008/0262220, US 7,612,199, US 2009/0130201 and Cryst. Eng. Comm., 2008, 10 1074-1081 (2008) disclose new forms of rifaximin.

WO 2008/035109 A1 discloses a process to prepare amorphous rifaximin, which comprises reaction of rifamycin S with 2-amino-4 picoline in presence of organic solvent like dichloromethane, ethylacetate, dichloroethylene, chloroform, in an inert atmosphere. When water is added to the reaction mixture, a solid precipitate corresponding to amorphous rifaximin is obtained.

The process described in this document can be assimilated to a crash precipitation, wherein the use of an anti-solvent causes the precipitation of rifaximin without giving any information about the chemical physical and biological characteristics of the rifaximin obtained.

WO 2009/108730 A2 describes different polymorphous forms of rifaximin and also amorphous forms of rifaximin. Amorphous forms are prepared by milling and crash precipitation and with these two different methods the amorphous rifaximin obtained from these two different processes has the same properties.

FIG. 4: 13C-NMR spectrum of rifaximin obtained by spray drying process.

FIG. 5: FT-IR spectrum of rifaximin obtained by spray drying process.


WO 2015014984

Rifaximin, lUPAC name:

(2S,16Z,18E,20S,21 S,22H,23H,24H,25S,26S,27S,28£)-5,6,21 ,23,25-pentahydroxy- 27-methoxy-2,4,1 1 ,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1 ,1 1 ,13]-trienimmino)-benzofuro-[4,5-e]-pirido-[1 ,2-oc]-benzimidazol-1 , 15(2 -/)-dione,25-acetate, is the compound of formula (I):

Rifaximin is a broad-spectrum antibiotic belonging to the family of rifamycins, devoid of systemic activity. In view of its physicochemical properties, it is not adsorbed in the gastrointestinal tract and therefore exerts its antimicrobial action inside the gastrointestinal tract. Rifaximin therefore has applications in the treatment of diarrhoea and of microbial infections of the gastrointestinal tract typically caused by E. coli, a microorganism which, being incapable of passing through the mucosa of the gastrointestinal tract, remains in contact with the gastrointestinal fluids. Rifaximin also has applications for the treatment of irritable bowel syndrome, Crohn’s disease, diverticulitis and for antibiotic prophylaxis preceding surgical operations on the intestines.

Rifaximin was obtained and described for the first time in the EP161534 starting from rifamycin O and 2-amino-4-picoline in the presence of ethanol/water and

ascorbic acid/HCI to obtain raw rifaximin which is then treated with Ethanol/water to obtain crystallized rifaximin.

Polymorphic forms of rifaximin, and processes for their synthesis and purification, are described in various documents of the known art.

Rifaximin K was firstly described in WO2012/156951 . Such a crystalline form resulted to be more stable in the presence of humidity than the other known crystalline forms of rifaximin, thus enabling the storage, even for prolonged periods. Such a polymorph was obtained by a process starting from rifaximin comprising the following steps: -suspending or dissolving rifaximin in a 1 ,2-dimethoxyethane based solvent, recovering the product and drying to remove said 1 ,2-dimethoxyethane based solvent. In one of the embodiments of the invention 1 ,2-dimethoxyethane is used as the unique solvent of rifaximin, in other 1 ,2-dimethoxyethane is described as used in combination of n-heptane, methanol, acetonitrile, R-COO-R1 esters wherein R and R1 are independently C3-C6 alkyl radicals, and C3-C7 alkyl ketones, ethanol, isopropanol and water.


The synthesis of 4-deoxypyrido(1′,2′-1,2)imidazo(5,4-c)rifamycin SV derivatives
J Antibiot 1984, 37(12): 1611