!e™A!a™Trp™leu™Va!~-Arg~~GIy-~Arg~~Gly~~OH

Formula (I)

LIRAGLUTIDE

Dr Reddy’s Laboratories Ltd, New patent, WO 2016005960,  Liraglutide

Process for preparation of liraglutide

Kola, Lavanya; Ramasamy, Karthik; Thakur, Rajiv Vishnukant; Katkam, Srinivas; Komaravolu, Yagna Kiran Kumar; Nandivada, Giri Babu; Gandavadi, Sunil Kumar; Nariyam Munaswamy, Sekhar; Movva, Kishore Kumar

Improved process for preparing liraglutide, by solid phase synthesis, useful for treating type 2 diabetes.

It having been developed and launched by Novo Nordisk, under license from Scios and Massachusetts General Hospital.

Liraglutide, marketed under the brand name Victoza, is a long-acting glucagon like peptide agonist developed by Novo Nordisk for the treatment of type 2 diabetes.

Liraglutide is an injectable drug that reduces the level of sugar (glucose) in the blood. It is used for treating type 2 diabetes and is similar to exenatide (Byetta). Liraglutide belongs to a class of drugs called incretin mimetics because these drugs mimic the effects of incretins. Incretins, such as human-glucagon-like peptide-1 (GLP-1 ), are hormones that are produced and released into the blood by the intestine in response to food. GLP-1 increases the secretion of insulin from the pancreas, slows absorption of glucose from the gut, and reduces the action of glucagon. (Glucagon is a hormone that increases glucose production by the liver.)

All three of these actions reduce levels of glucose in the blood. In addition, GLP-1 reduces appetite. Liraglutide is a synthetic (man-made) hormone that resembles and acts like GLP-1 . In studies, Liraglutide treated patients achieved lower blood glucose levels and experienced weight loss.

Liraglutide, an analog of human GLP-1 acts as a GLP-1 receptor agonist. The peptide precursor of Liraglutide, produced by a process that includes expression of recombinant DNA in Saccharomyces cerevisiae, has been engineered to be 97% homologous to native human GLP-1 by substituting arginine for lysine at position 34. Liraglutide is made by attaching a C-16 fatty acid (palmitic acid) with a glutamic acid spacer on the remaining lysine residue at position 26 of the peptide precursor.

The molecular formula of Liraglutide is Ci₇₂H₂65N₄30₅i and the molecular weight is 3751 .2 Daltons. It is represented by the structure of formula (I)

!e™A!a™Trp™leu™Va!~-Arg~~GIy-~Arg~~Gly~~OH

Formula (I)

U.S. Patent No. 7572884 discloses a process for preparing Liraglutide by recombinant technology followed by acylation and removal of N-terminal extension.

U.S. Patent No. 7273921 and 6451974 discloses a process for acylation of Arg-³⁴GLP-1 (7-37) to obtain Liraglutide.

U.S. Patent No. 8445433 discloses a solid phase synthesis of Liraglutide using a fragment approach.

International Application publication No. WO2013037266A1 discloses solid phase synthesis of Liraglutide, characterized in that comprises A) the presence of the activator system, solid phase carrier and by resin Fmoc protection N end obtained by coupling of glycine (Fmoc-Gly-OH) Fmoc-Gly-resin; B) by solid phase synthesis, prepared in accordance with the sequentially advantage Liraglutide principal chain N end of the coupling with Fmoc protected amino acid side chain protection and, wherein the lysine using Fmoc-Lys (Alloc)-OH; C) Alloc getting rid of the lysine side chain protecting group; D) by solid phase synthesis, the lysine side chain coupling Palmitoyl-Glu-OtBu; E) cracking, get rid of protecting group and resin to obtain crude Liraglutide ; F) purification, freeze-dried, to obtain Liraglutide.

Even though, the above mentioned prior art discloses diverse processes for the preparation of Liraglutide, they are often not amenable on commercial scale because of expensive amino acid derivatives such as pseudo prolines used in those processes.

Hence, there remains a need to provide simple, cost effective, scalable and robust processes for the preparation of Liraglutide involving commercially viable amino acid derivatives and reagents.

EXAMPLE 1 :

Stage I Preparation of Wang resin-Gly-Arg(pbf)-Gly-Arg(pbf)-Val-Leu-Trp(Boc)-Ala-lleu-Phe-Glu(Otbu)-Lys-{Glu(OH)-NH(palmitoyl)}-Ala-Ala-Gln(trt)-Gly-OH-Glu(Otbu)-Leu-Tyr(Otbu)-Ser(Otbu)-Ser(Otbu)-Val-Asp(Otbu)-Ser(Otbu)-Thr(Otbu)-Phe-Thr(Otbu)-Gly-Glu(Otbu)-Ala-Boc-His(trt)-OH.

Wang resin (50gm) is swelled in DCM (500ml) for 1 hr in a sintered flask. DCM was filtered using Vacuum. Fmoc-Glycine (44.6 gm, 150 mmol) was dissolved in dichloromethane (250 ml). 1 -(2-mesitylene sulfonyl)-3-nitro-1 H-1 ,2,4 triazole (44.4 gm, 150 mmol) and 1 -methyl imidazole (9 ml, 1 12 mmol) was then added. The reaction mixture was added to wang resin and stirred for 3hrs at about 25° C. The resin was washed with DCM and a second lot of Fmoc-Glycine (27 gm, 90 mmol) was dissolved in dichloromethane (250 ml). 1 -(2-mesitylene sulfonyl)-3-nitro-1 H-1 ,2,4 triazole (26.6 gm, 90 mmol) and 1 -methyl imidazole (5.3 ml, 90 mmol) was then added and stirred for 3hrs. The resin was washed with DCM and a sample of resin beads were checked for UV analysis. The capping was carried out using acetic anhydride (15 ml) DCM (120 ml) and pyridine (120 ml). The resin was washed with dichloromethane and DMF. The Fmoc protecting group was removed by treatment with 20% piperidine in DMF. The

resin was washed repeatedly with DMF. The next amino acid Fmoc-Arg(pbf)-OH (52 gm, 80 mmol) dissolved in 250 ml DMF was then added. The coupling was carried out by addition of HOBt (10.8gm, 80 mmol) and DIC (6.2ml, 80 mmol) in DMF. The completion of the coupling was confirmed by a ninhydrin test. After washing the resin, the Fmoc protecting group was removed with 20% piperidine in DMF. These steps were repeated each time with the respective amino acid according to the peptide sequence. After coupling 12^th amino acid Fmoc-Lys (Alloc)-OH, deprotection of alloc group is carried out with palladium tetrakis and phenyl silane in DCM. The resin was washed repeatedly with DMF. The next amino acid H-Glu(OH)-NH(palmitoyl)-Otbu (9.9 gm, 0.023 moles) dissolved in 250 ml DMF was then added. The coupling was carried out by addition of HOBt (10.8gm, 80 mmol) and DIC (6.2ml, 80 mmol) in DMF. The completion of the coupling was confirmed by a ninhydrin test. After washing the resin, the Fmoc protecting group of Lys was removed with 20% piperidine in DMF. The next amino acid Fmoc-Ala-OH (52 gm, 80 mmol) dissolved in 250 ml DMF was then added. The coupling was carried out by addition of HOBt (10.8gm, 80 mmol) and DIC (6.2ml, 80 mmol) in DMF. The completion of the coupling was confirmed by a ninhydrin test. After washing the resin, the Fmoc protecting group was removed with 20% piperidine in DMF. These steps were repeated each time with the respective amino acid according to the peptide sequence. The resin was washed repeatedly with DMF, Methanol and MTBE and dried under vacuum.

Stage II: Cleavage of Liraglutide from resin along with global deprotection

45gms of resin obtained in stage I was treated with cleavage cocktail mixture of TFA (462.5ml), TIPS (12.5ml), Water (12.5ml), and Phenol (12.5 ml), stirred at 0°C for 30 min. and at 25°C for 3hrs at 200RPM. Then the reaction mixture was filtered, repeatedly wash the resin with TFA and the filtrate was concentrated on Rotary evaporator at 30°C. Pour the concentrated solution to MTBE (2L) at 4°C slowly and stir for 1 hr. The precipitate obtained is filtered and dried in a vacuum tray drier to afford 18 gm of Liraglutide crude with a purity of 27.5%.

Stage III: Purification of crude Liraglutide using RP HPLC.

The crude Liraglutide (4 gm) of purity around 27.5% is dissolved in 10 mM Tris buffer (120ml) of pH: 8.00 and 0.5 N NaOH is further added drop wise to the solution for making the crude solid completely dissolved. The solution is further passed through 0.2 micron filter. The Reverse phase C 18 – 150 Angstrom media (C18 silica media – 10 micron particle size) is equilibrated with 10mM Tris buffer of pH: 8.0 The crude solution is loaded onto the column and the gradient elution is performed as per the below tabular column against the mobile phase B (Acetonitrile).

Table 1 : Gradient program for pre purification

The desired fractions are collected in the gradient range of and the fractions (F1 , F2, F3, F4 and F5) whose purity > 80% are pooled. The pooled fractions are then subjected to further purification.

The Pooled fractions having purity >80% are then subjected to C18 RPHPLC silica media (5 micron particle size) for further purification. The pooled fractions – Feed is diluted with purified water in the ratio of 1 :2 (one part of pooled fraction to two parts of purified water) as a part of sample preparation before loading into the column. The media C18 is first equilibrated with 0.1 % TFA for 3 column volumes (1 CV = bed volume of media). After equilibration, the sample is loaded onto the column and the gradient

elution is performed as per the below tabular column against the mobile phase B (Acetonitrile).

Table 2: Gradient program for second purification

The desired fractions are collected in the gradient range of and the fraction whose purity > 96% are pooled together and lyophilized to afford 220mg of Liraglutide trifluoro acetate salt. The pooled fractions and their purity by HPLC are listed in the below table.

The pooled fractions with the purity of average 97% are subjected further to de solvation to remove the Acetonitrile content by Rota vapor. The final solution was filtered through 0.2 micron filter and lyophilized to get Liraglutide API.

EXAMPLE 2:

Stage I Preparation of Tentagel SPHB resin-Gly-Arg(pbf)-Gly-Arg(pbf)-Val-Leu-Trp(Boc)-Ala-lleu-Phe-Glu(Otbu)-Lys-{Glu(OH)-NH(palmitoyl)}-Ala-Ala-Gln(trt)-Gly-OH-Glu(Otbu)-Leu-Tyr(Otbu)-Ser(Otbu)-Ser(Otbu)-Val-Asp(Otbu)-Ser(Otbu)-Thr(Otbu)-Phe-Thr(Otbu)-Gly-Glu(Otbu)-Ala-Boc-His(trt)-OH using Fragment approach.

Fragments used are as follows

1 . Fmoc-Arg(pbf)-Gly-OH.

2. Fmoc-Leu-Ala-Arg(pbf)-OH.

3. Fmoc-lle-Ala-Trp(boc)-OH.

4. Fmoc-Glu(Otbu)-Phe-OH.

5. Fmoc-Glu(Otbu)-Phe-OH.

6. Fmoc-Lys-Glu-Palmitic acid.

7. Fmoc-Gly-Gln(trt)-Ala-Ala-OH.

8. Fmoc-Tyr(Otbu)-Leu-Glu(Otbu)-OH.

9. Fmoc-Val-Ser(Otbu)-Ser(Otbu)-OH.

10. Fmoc-Phe-Thr(Otbu)-Ser(Otbu)-Asp(Otbu)-OH

1 1 . Fmoc-Gly-Thr(Otbu)-OH.

12. Boc-His(Trt)-Ala-Glu(Otbu)-OH.

Tentagel SPHB resin (30gm) is swelled in DCM (300ml) for 1 hr in a sintered flask. DCM was filtered using Vacuum. Fmoc-Glycine (13.8 gm, 46.8 moles) was dissolved in dichloromethane (150 ml). 1 -(2-mesitylene sulfonyl)-3-nitro-1 H-1 ,2,4 triazole (13.8 gm, 46.8 moles) and 1 -methyl imidazole (2.4 ml, 29.25 moles) was then added. The resulting solution was added to tentagel resin and stirred for 2hrs at about 25° C. The resin was washed with DCM and a second lot of Fmoc-Glycine (13.8 gm, 46.8 moles) was dissolved in dichloromethane (150 ml). 1 -(2-mesitylene sulfonyl)-3-nitro-I H-1 ,2,4 triazole (13.8 gm, 46.8 moles) and 1 -methyl imidazole (2.4 ml, 29.25 moles) was then added and stirred for 2hrs. The resin was washed with DCM and a sample of resin beads were checked for UV analysis. The Fmoc protecting group was removed by treatment with 20% piperidine in DMF. The resin was washed repeatedly

with DMF. The next amino acid fragment 1 Fmoc-Gly-Arg(pbf)-OH (8.25 gm, 1 1 .7 moles) dissolved in 150 ml DMF was then added. The coupling was carried out by addition of HOBt (2.1 gm, 1 1 .7 moles) and DIC (2.5ml, 1 1 .7 moles) in DMF for 2hrs. The completion of the coupling was confirmed by a ninhydrin test. After washing the resin, the Fmoc protecting group was removed with 20% piperidine in DMF. These steps were repeated each time with the respective amino acid fragments according to the peptide sequence. The resin was washed repeatedly with DMF, Methanol and MTBE and dried under vacuum.

Stage II: Cleavage of Liraglutide from resin along with global deprotection

58gms of resin obtained from stage I was treated with cleavage cocktail mixture of TFA (555ml), TIPS (15ml), Water (15ml), and Phenol (15 ml) and stirred at 0°C for 30 min. at 25°C for 3hrs at 200RPM. Then filter the reaction mixture, repeatedly wash the resin with TFA and concentrate on Rotary evaporator at 30°C. Pour the concentrated solution to MTBE at 4°C slowly and stirred for 1 hr. The precipitate obtained was filtered and dried in a vacuum tray drier to afford 23.12 gm of crude Liraglutide with a purity of 36.89%.

Stage III: Purification of crude Liraglutide using RP HPLC.

The crude Liraglutide (4 gm) of purity around 27.5% is dissolved in 10 mM Tris buffer (120ml) of pH: 8.00 and 0.5 N NaOH is further added drop wise to the solution for making the crude solid completely dissolved. The solution is further passed through 0.2 micron filter. The Reverse phase C 18 – 150 Angstrom media (Irregular C18 silica media – 10 micron particle size) is equilibrated with 10mM Tris buffer of pH: 8.0 The crude solution is loaded onto the column and the gradient elution is performed as per the below tabular column against the mobile phase B (Acetonitrile).

Table 1 : Gradient program for pre purification

60 40 30

55 45 30

52 48 30

51 49 60

The desired fractions are collected in the gradient range of and the fractions (F1 , F2, F3, F4 and F5) whose purity > 80% are pooled. The pooled fractions then subjected to further purification.

The Pooled fractions having purity >80% are then subjected to C18 RPHPLC silica media (5 micron particle size) for further purification. The pooled fractions – Feed is diluted with purified water in the ratio of 1 :2 (one part of pooled fraction to two parts of purified water) as a part of sample preparation before loading into the column. The media C18 is first equilibrated with 0.1 % TFA for 3 column volumes (1 CV = bed volume of media). After equilibration, the sample is loaded onto the column and the gradient elution is performed as per the below tabular column against the mobile phase B (Acetonitrile).

Table 2: Gradient program for second purification

The desired fractions are collected in the gradient range and the fraction whose purity > 96% are pooled together and Lyophilized to afford 865 mg of Liraglutide trifluoro acetate salt. The pooled fractions and their purity by HPLC are listed in the below table.

The pooled fractions with the purity of average 97% are subjected further to de solvation to remove the Acetonitrile content by Rota vapor. The final solution was filtered through 0.2 micron filter and lyophilized to get Liraglutide API.

G.V. Prasad, chairman, Dr Reddy’s Laboratories.

REFERENCE

IN2014CH3453 INDIAN PATENT

WO 2016005960, CLICK FOR PATENT

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