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A positive genotoxicity result can throw the fate of a promising drug candidate—in which a firm has invested significant time and money—into doubt

A positive genotoxicity result can throw the fate of a promising drug candidate-in which a firm has invested significant time and money-into doubt. The statistical improbability and challenges of bringing a drug to market become paramount.
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BY WORLD DRUG TRACKER
Automating Lead Optimization
This diagram illustrates the methods used to determine solubility as a compound advances toward further clinical study, and the increasing reach of automation and informatics systems. Initially, screens are run in silico on a library after hits are determined through a high-throughput screen; then various kinetic solubility assays are used to determine the compound’s potency at various concentrations. Two rounds of kinetic solubility assays determine gross and broad solubility (mmol/L) and finite solubility (less than 20 µmol/L) before the compound is advanced into thermodynamic solubility assays. Figure modified from Petereit A, Saal C. What is the Solubility of My Compound? Assessing Solubility for Pharmaceutical Research and Development Compounds. Am Pharm Rev. 2011; 14
The drug discovery business is changing rapidly. More pharmaceutical companies are working with smaller biotech firms to create early-stage compounds, and thus need quicker and standardized solutions to early-stage development problems.
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WORLD DRUGTRACKER
Gilead Announces U.S. FDA Priority Review Designation for Sofosbuvir for the Treatment of Hepatitis C
Sofosbuvir
Isopropyl (2S)-2-[[[(2R,3R,4R,5R)-5-(2,4-dioxopyrimidin-1-yl)-4-fluoro-3-hydroxy-4-methyl-tetrahydrofuran-2-yl]methoxy-phenoxy-phosphoryl]amino]propanoate
http://www.ama-assn.org/resources/doc/usan/sofosbuvir.pdf –for cas no
Jun. 7, 2013– Gilead Sciences, Inc. today announced that the U.S. Food and Drug Administration (FDA) has granted priority review to the company’s New Drug Application (NDA) for sofosbuvir, a once-daily oral nucleotide analogue inhibitor for the treatment of chronic hepatitis C virus (HCV) infection. The FDA grants priority review status to drug candidates that may offer major advances in treatment over existing options. Gilead filed the NDA for sofosbuvir on April 8, 2013, and FDA has set a target review date under the Prescription Drug User Fee Act (PDUFA) of December 8, 2013.

The data submitted in this NDA support the use of sofosbuvir and ribavirin (RBV) as an all-oral therapy for patients with genotype 2 and 3 HCV infection, and for sofosbuvir in combination with RBV and pegylated interferon (peg-IFN) for treatment-naïve patients with genotype 1, 4, 5 and 6 HCV infection.
Sofosbuvir is an investigational product and its safety and efficacy have not yet been established.
About Gilead Sciences
Gilead Sciences is a biopharmaceutical company that discovers, develops and commercializes innovative therapeutics in areas of unmet medical need. The company’s mission is to advance the care of patients suffering from life-threatening diseases worldwide. Headquartered in Foster City, California, Gilead has operations in North America, Europe and Asia Pacific.
Sofosbuvir (formerly PSI-7977 or GS-7977) is an experimental drug candidate for the treatment of hepatitis C.[1] It was discovered at Pharmasset and then acquired for development by Gilead Sciences. It is currently in Phase III clinical trials.[2]
Sofosbuvir is a prodrug that is metabolized to the active antiviral agent 2′-deoxy-2′-α-fluoro-β-C-methyluridine-5′-monophosphate.[3]
Sofosbuvir is a nucleotide analogue inhibitor of the hepatitis C virus (HCV) polymerase.[4] The HCV polymerase or NS5B protein is a RNA-dependent RNA polymerase critical for the viral cycle.
Sofosbuvir is being studied in combination with pegylated interferon and ribavirin, with ribavirin alone, and with other direct-acting antiviral agents.[5] It has shown excellent clinical efficacy when used either with pegylated interferon/ribavirin or in interferon-free combinations. In particular, combinations of sofosbuvir with NS5A inhibitors, such as daclatasvir or GS-5885, have shown sustained virological response rates of up to 100% in people infected with HCV.[6]
Data from the ELECTRON trial showed that a dual interferon-free regimen of sofosbuvir plus ribavirin produced a 24-week post-treatment sustained virological response (SVR24) rate of 100% for previously untreated patients with HCV genotypes 2 or 3.[7][8]
Data presented at the 20th Conference on Retroviruses and Opportunistic Infections in March 2013 showed that a triple regimen of sofosbuvir, ledipasvir (formerly GS-5885), and ribavirin produced a 12-week post-treatment sustained virological response (SVR12) rate of 100% for both treatment-naive patients and prior non-responders with HCV genotype 1.[9]Gilead has developed a sofosbuvir + ledipasvir coformulation that is being tested with and without ribavirin.

- Sofia, M. J.; Bao, D.; Chang, W.; Du, J.; Nagarathnam, D.; Rachakonda, S.; Reddy, P. G.; Ross, B. S. et al. (2010). “Discovery of a β-d-2′-Deoxy-2′-α-fluoro-2′-β-C-methyluridine Nucleotide Prodrug (PSI-7977) for the Treatment of Hepatitis C Virus”. Journal of Medicinal Chemistry 53 (19): 7202–7218. doi:10.1021/jm100863x. PMID 20845908. edit
- “PSI-7977″. Gilead Sciences.
- Murakami, E.; Tolstykh, T.; Bao, H.; Niu, C.; Steuer, H. M. M.; Bao, D.; Chang, W.; Espiritu, C. et al. (2010). “Mechanism of Activation of PSI-7851 and Its Diastereoisomer PSI-7977″. Journal of Biological Chemistry 285 (45): 34337–34347.doi:10.1074/jbc.M110.161802. PMC 2966047. PMID 20801890. edit
- Alejandro Soza (November 11, 2012). “Sofosbuvir”. Hepaton.
- Tom Murphy (November 21, 2011). “Gilead Sciences to buy Pharmasset for $11 billion”. Bloomberg Businessweek.
- http://www.gilead.com/pr_1757156
- AASLD: PSI-7977 plus Ribavirin Can Cure Hepatitis C in 12 Weeks without Interferon. Highleyman, L. HIVandHepatitis.com. 8 November 2011.
- Nucleotide Polymerase Inhibitor Sofosbuvir plus Ribavirin for Hepatitis C. Gane, E et al. New England Journal of Medicine 368:3444. January 3, 2013.
- CROI 2013: Sofosbuvir + Ledipasvir + Ribavirin Combo for HCV Produces 100% Sustained Response. Highleyman, L. HIVandHepatitis.com. 4 March 2013.
Eating Broccoli Reduces Risk of Cardiovascular Disease, Promotes Heart Health

by Elizabeth Renter , MY SCIENCE ACADEMY
It’s not good enough to know that vegetables like broccoli are healthful; we need to know specifically what sort of benefits they deliver, how they deliver those benefits and how we can make the most of them.
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Japanese drugmaker Kyowa Hakko Kirin (TYO: 4151) say that it launched its novel Parkinson’s disease drug Nouriast (istradefylline) in Japan on May 30.
Istradefylline (KW-6002), 8-[(E)-2-(3,4-dimethoxyphenyl)vinyl]-1,3-diethyl-7-methyl-3,7-dihydro-1H-purine-2,6-dione, is a selective antagonist at the A2A receptor. It has been found to be useful in the treatment of Parkinson’s disease.[1] Istradefylline reduces dyskinesia resulting from long-term treatment with classical antiparkinson drugs such as levodopa. Istradefylline is an analog of caffeine.
1–
- Peter A. LeWitt, MD, M. Guttman, James W. Tetrud, MD, Paul J. Tuite, MD, Akihisa Mori, PhD, Philip Chaikin, PharmD, MD, Neil M. Sussman, MD (2008). “Adenosine A2A receptor antagonist istradefylline (KW-6002) reduces off time in Parkinson’s disease: A double-blind, randomized, multicenter clinical trial (6002-US-005)”. Annals of Neurology 63 (3): 295–302. doi:10.1002/ana.21315. PMID 18306243.
Nouriast, which is the world’s first anti-parkinsonian agent of a first-in-class adenosine A2A receptor antagonist, was listed on the National Health Insurance Drug Price List on May 24, 2013 after the manufacturing and marketing approval in Japan on March 25, the company noted. In clinical trials in Japan, Nouriast improved wearing-off phenomena and was well tolerated in Parkinson’s disease patients
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Otsuka Pharmaceutical Submits New Drug Application in Japan for Tolvaptan for the Treatment of Autosomal Dominant Polycystic Kidney Disease (ADPKD)
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TOLVAPTAN
may 30 2013
- Tolvaptan was discovered by Otsuka in Japan, and its primary results from a global clinical trial involving 1,400 ADPKD patients from 15 countries, which demonstrated a statistically significant reduction in the rate of total kidney volume, were published in New England Journal of Medicine in 2012. It is also currently under a fast track review in the US, following our announcement of FDA accepting to review the application in April 2013.
- ADPKD is a hereditary and often physically and mentally burdensome disease characterized by the development of multiple cysts in the kidneys. ADPKD is often associated with pain, hypertension, decreased kidney function and ultimately, kidney failure that may result in hemodialysis or kidney transplantation.
- There are estimated to be approximately 31,000 ADPKD patients in Japan, and the diagnosed prevalence is estimated to be between 1:1000 and 1:4000 globally.
(Tokyo, Japan, May 30, 2013) – Otsuka Pharmaceutical Co., Ltd. Today announced it filed an application with the Pharmaceutical and Medical Devices Agency in Japan (PMDA) to market its novel compound tolvaptan for the treatment of Autosomal Dominant Polycystic Kidney Disease (ADPKD). Phase III clinical trial results that form the basis of the regulatory filing were published in the New England Journal of Medicine in November 2012. The MHLW has designated tolvaptan as an Orphan Drug.http://www.otsuka.co.jp/en/release/2013/0603_02.html
Tolvaptan (INN), also known as OPC-41061, is a selective, competitive vasopressin receptor 2 antagonist used to treat hyponatremia (low blood sodium levels) associated withcongestive heart failure, cirrhosis, and the syndrome of inappropriate antidiuretic hormone(SIADH). Tolvaptan was approved by the U.S. Food and Drug Administration (FDA) on May 19, 2009, and is sold by Otsuka Pharmaceutical Co. under the trade name Samsca and in India is manufactured & sold by MSN laboratories Ltd. under the trade name Tolvat & Tolsama.
Tolvaptan is also in fast-track clinical trials[2] for polycystic kidney disease. In a 2004 trial, tolvaptan, when administered with traditional diuretics, was noted to increase excretion of excess fluids and improve blood sodium levels in patients with heart failure without producing side effects such as hypotension (low blood pressure) or hypokalemia(decreased blood levels of potassium) and without having an adverse effect on kidney function.[3] In a recently published trial (TEMPO 3:4 ClinicalTrials.gov number, NCT00428948) the study met its primary and secondary end points. Tolvaptan, when given at an average dose of 95 mg per day over a 3-year period, slowed the usual increase in kidney volume by 50% compared to placebo (2.80% per year versus 5.51% per year, respectively, p<0.001) and reduced the decline in kidney function when compared with that of placebo-treated patients by approximately 30% (reciprocal serum creatinine, -2.61 versus -3.81 (mg/mL)-1 per year, p <0.001)[4]
Chemical synthesis:[5] ![]()
- Shoaf S, Elizari M, Wang Z, et al. (2005). “Tolvaptan administration does not affect steady state amiodarone concentrations in patients with cardiac arrhythmias”. J Cardiovasc Pharmacol Ther 10 (3): 165–71. doi:10.1177/107424840501000304. PMID 16211205.
- Otsuka Maryland Research Institute, Inc.
- Gheorghiade M, Gattis W, O’Connor C, et al. (2004). “Effects of tolvaptan, a vasopressin antagonist, in patients hospitalized with worsening heart failure: a randomized controlled trial”. JAMA 291 (16): 1963–71. doi:10.1001/jama.291.16.1963. PMID 15113814.
- (2012) Tolvaptan in Patients with Autosomal Dominant Polycystic Kidney Disease
- Kondo, K.; Ogawa, H.; Yamashita, H.; Miyamoto, H.; Tanaka, M.; Nakaya, K.; Kitano, K.; Yamamura, Y.; Nakamura, S.; Onogawa, T.; et al.; Bioor. Med. Chem. 1999, 7, 1743.
- http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm350185.htm?source=govdelivery
- Gheorghiade M, Niazi I, Ouyang J et al. (2003). “Vasopressin V2-receptor blockade with tolvaptan in patients with chronic heart failure: results from a double-blind, randomized trial”. Circulation 107 (21): 2690–6. doi:10.1161/01.CIR.0000070422.41439.04.PMID 12742979.
New study reveals Iron supplementation may help Velcade work better
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bortezomib
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Bortezomib (INN, originally codenamed PS-341; marketed as Velcade by Millennium Pharmaceuticals) is the first therapeutic proteasome inhibitor to be tested in humans. It is approved in the U.S. for treating relapsed multiple myeloma and mantle cell lymphoma. In multiple myeloma, complete clinical responses have been obtained in patients with otherwise refractory or rapidly advancing disease.
Bortezomib was originally synthesized in 1995 (MG-341) at a company called Myogenics, which soon changed its name to ProScript. After promising preclinical results, the drug (PS-341) was tested in a small Phase I clinical trial on patients with multiple myeloma cancer. ProScript ran out of money and was bought by Leukosite in May 1999. Leukosite in turn was bought by Millennium Pharmaceuticals in October 1999. At this point in time, the project had low priority amongst other projects at the company. This changed significantly when one of the first volunteers to receive the drug in the clinical trial achieved a complete response and were still alive four years later. At the time this was a remarkable result. Later clinical experimentation indicates the possibility of a complete response in 15% of patients in a similar condition, when treated with bortezomib.
In May 2003, seven years after the initial synthesis, bortezomib (Velcade) was approved in the United States by the Food and Drug Administration (FDA) for use in multiple myeloma, based on the results from the SUMMIT Phase II trial.
Another commercially available bortezomib product – Bortenat (Natco Pharma, India), reportedly contains substantially more active entity than declared, potentially and even more resulting in increase toxicity. Moreover, Bortenat has some other chemical and formulation deviations from the registered ethic product Velcade (Millennium Pharmaceuticals and Janssen-Cilag), with unclear clinical impact.
Pharmacology
Bortezomib bound to the core particle in a yeast proteasome. The bortezomib molecule is in the center colored by atom type (boron = pink, carbon = cyan, nitrogen = blue, oxygen = red), surrounded by the local protein surface. The blue patch is catalytic threonine residue whose activity is blocked by the presence of bortezomib.
Structure
The drug is an N-protected dipeptide and can be written as Pyz-Phe-boroLeu, which stands for pyrazinoic acid, phenylalanine and Leucine with a boronic acid instead of a carboxylic acid. Peptides are written N-terminus to C-terminus, and this convention is used here even though the “C-terminus” is a boronic acid instead of a carboxylic acid.
FDA panel urges looser restrictions on diabetes drug Avandia
june 6 2013,
The controversial diabetes drug Avandia will get a second look from federal regulators this week, nearly two years after its use was severely restricted because of a link to heart problems.
The U.S. Food and Drug Administration has convened a panel of experts to consider an independent review by Duke University researchers of Avandia’s original clinical trial. The expert panel will conclude its sessions on Thursday, and could decide to alter or even lift the tight restrictions now in place regarding the medication’s use.

The Duke scientists did uncover some previously unreported cases of heart complications and deaths, but concluded that these cases did not significantly raise the overall risk of heart disease and the conclusions of the original trial still hold.
The FDA’s reconsideration of Avandia’s safety has prompted stinging criticism from the drug’s detractors, who say the agency is trying to save face following a very public embarrassment over the drug.

“This is a drug that has essentially been off the market in almost the entire world for the last three years. It has been banned in most countries, and is available in the United States under such strict requirements that only 3,000 patients now take it,” said Dr. Steven Nissen, the Cleveland Clinic cardiologist who first led the charge against Avandia. “It’s really about the FDA wanting to clean up its image, not about whether the drug is actually safe or unsafe.”
The FDA has defended its decision to review the Duke re-analysis of the original trial, which was conducted by the drug’s maker, GlaxoSmithKline, under the name Rosiglitazone Evaluated for Cardiovascular Outcomes and Regulation of Glycemia in Diabetes (RECORD).
“Given the public interest in Avandia, the extensive history of the product and the continued uncertainty of risk, the FDA is holding the advisory committee meeting to have a transparent, public discussion of the results of the RECORD readjudication,” FDA spokesperson Morgan Liscinsky said.
Avandia quickly became a blockbuster diabetes drug following its release in 1999, with sales topping $3 billion in 2006.
Eisai Announces Availability of BELVIQ® (lorcaserin HCl) CIV Tablets for Chronic Weight Management in Adults who are Overweight with a Comorbidity or Obese BELVIQ Available in U.S. Pharmacies within One Week
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LORCASERIN
june 7, 2013 –Eisai Inc. announced today that BELVIQ (pronounced BEL-VEEK) will be available to eligible patients by prescription in the United States beginning June 11.
BELVIQ was approved by the U.S. Food and Drug Administration on June 27, 2012 to be used along with a reduced-calorie diet and increased physical activity for chronic weight management in adults who have a body mass index (BMI) of 30 kg/m2 or greater (obese), or BMI of 27 kg/m2 or greater (overweight) with at least one weight-related medical condition such as high blood pressure, high cholesterol, or type 2 diabetes. It is not known if BELVIQ is safe and effective when taken with other prescription, over-the-counter, or herbal weight loss products, nor is it known if BELVIQ changes your risk of heart problems or stroke, or of death due to heart problems or stroke.
“BELVIQ is a new treatment option for the medical management of patients who are obese and who have not been able to sustain long-term weight loss by altering their diets or increasing exercise alone,” said Lonnel Coats, President and Chief Executive Officer, Eisai Inc. “Eisai is committed to making BELVIQ available to appropriate patients as part of our human health care corporate mission of keeping patients’ medical needs at the forefront of all that we do.”
BELVIQ will be available in U.S. pharmacies only with a prescription. Patients are cautioned not to buy BELVIQ from parties offering BELVIQ without a valid prescription from their doctor. Eisai will market and distribute BELVIQ in the United States and Arena Pharmaceuticals will manufacture and supply the finished commercial product from its facility in Switzerland.
“BELVIQ provides appropriate patients with a new treatment option that along with diet and exercise can help them lose weight and keep the weight off,” said Ken Fujioka, M.D., Director of the Center for Weight Management at the Scripps Clinic. “Obesity needs to be recognized and treated as a chronic disease. The availability of BELVIQ is a significant milestone in the medical management of overweight and obesity as we work to slow this epidemic in the United States.”
Lorcaserin (APD-356, trade name upon approval Belviq,expected trade name during development, Lorqess) is a weight-loss drug developed by Arena Pharmaceuticals. It has serotonergic properties and acts as an anorectic. On 22 December 2009 a New Drug Application (NDA) was submitted to the Food and Drug Administration (FDA) in the United States.On 16 September 2010, an FDA advisory panel voted to recommend against approval of the drug based on concerns over both safety and efficacy. In October 2010, the FDA stated that it could not approve the application for lorcaserin in its present form.
On 10 May 2012, after a new round of studies submitted by Arena, an FDA panel voted to recommend lorcaserin with certain restrictions and patient monitoring. The restrictions include patients with a BMI of over 30, or with a BMI over 27 and a comorbidity like high blood pressure or type 2 diabetes.
On 27 June 2012, the FDA officially approved lorcaserin for use in the treatment of obesity for adults with a BMI equal to or greater than 30 or adults with a BMI of 27 or greater who “have at least one weight-related health condition, such as high blood pressure, type 2 diabetes, or high cholesterol”.
On 07 May 2013, the US Drug Enforcement Administration has classified lorcaserin as a Schedule IV drug[10] under the Controlled Substances Act.
About BELVIQ (lorcaserin HCl) CIV Tablets
BELVIQ is believed to decrease food consumption and promote satiety by selectively activating serotonin 2C receptors in the brain. The exact mechanism of action of BELVIQ is not known. BELVIQ is a federally controlled substance (CIV) because it may be abused or lead to drug dependence. For more information about BELVIQ,
Tribulus terrestris-considered as an energizer and vitalizer in the indigenous system of medicine
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Tribulus terrestris
Tribulus terrestris is a flowering plant in the family Zygophyllaceae, native to warm temperate and tropical regions of the Old World in southern Europe, southern Asia, throughout Africa, and Australia. It can thrive even in desert climates and poor soil. Like many weedy species, this plant has many common names, including bindii, bullhead, burra gokharu, caltrop, cat’s head, devil’s eyelashes, devil’s thorn, devil’s weed, goathead, puncturevine, and tackweed.
In traditional Chinese medicine Tribulus terrestris is known under the name bai ji li (白蒺藜). According to Bensky and Clavey, 2004 (Materia medica 3rd edition, pp. 975–976) Tribulus terrestris is ci ji li (刺蒺藜). “Confusion with Astragali complanati Semen (sha yuan zi) originally known as white ji li (白蒺藜 bai ji li), led some writers to attribute tonifying properties to this herb…”
T. terrestris has long been a constituent in tonics in Indian Ayurveda practice, where it is known by its Sanskrit name, “gokshura/ sarrata” It is also used in Unani, another medical system of India.
Apart from its claims for improvement of sexual functions in men, the puncturevine plant (Tribulus terrestris: TT) has long been considered as an energizer and vitalizer in the indigenous system of medicine. Sexual behavior and intracavernous pressure (ICP) measurements were taken in rats to scientifically validate the claim of TT [containing protodioscin (PTN)] as an aphrodisiac.
http://www.ncbi.nlm.nih.gov/pubmed/12804079
Tribulus has chemicals that might increase some hormones in animals. However, it doesn’t appear to increase male hormones (testosterone) in humans.
Chemical control is generally recommended for home control of T. terrestris. There are few pre-emergent herbicides that are effective. Products containing oryzalin, benefin, or trifluralin will provide partial control of germinating seeds. These must be applied prior to germination (late winter to midspring).
After plants have emerged from the soil (postemergent), products containing 2,4-dichlorophenoxyacetic acid (“2,4-D”), glyphosate, anddicamba are effective on T. terrestris. Like most postemergents, they are more effectively maintained when caught small and young. Dicamba and 2,4-D will cause harm to most broad-leaved plants, so the user should take care to avoid over-application. They can be applied to lawns without injuring the desired grass. Glyphosate will kill or injure most plants, so it should only be used as a spot treatment or on solid stands of the weed.
Simmer 500 mg of powered tribulus in organic milk or almond milk, stirring constantly for 5 minutes. You can add 500 mg of standardized maca to enhance the effect. This blend is particularly nourishing and is recommended for both men and women who have lowered libido
Tribulus is a plant that produces fruit covered with spines. Rumor has it that tribulus is also known as puncture vine because the spines are so sharp they can flatten bicycle tires. People use the fruit, leaf, and root as medicine for wide-ranging complaints.
Tribulus is used for kidney problems, including kidney stones, painful urination, a kidney disorder called Bright’s disease, and as a “water pill” (diuretic) to increase urination; for skin disorders, including eczema (atopic dermatitis), psoriasis, andscabies; for male sexual problems, including erectile dysfunction (ED), involuntary release of semen without orgasm (spermatorrhea), and to increase sexual desire; for heart and circulatory system problems, including chest pain, high blood pressure,high cholesterol, and “tired blood” (anemia); for problems with digestion, including colic, intestinal gas (flatulence), constipation, and to expel intestinal parasitic worms; for pain and swelling (inflammation) of the tissue lining the mouth (stomatitis) andsore throat; and for cancer, especially nose tumors.
Women use tribulus to tone muscles before childbirth, to cause an abortion, and to stimulate milk flow.
Some people use tribulus for gonorrhea, liver disease (hepatitis), inflammation, joint pain (rheumatism), leprosy, coughs, headache, dizziness (vertigo), chronic fatiguesyndrome (CFS), and enhancing athletic performance. It is also used for stimulating appetite and as an astringent, tonic, and mood enhancer.
recap
Tribulus terrestris, also known as puncture vine, is a herb that has been used in the traditional medicine of China and India for centuries.
In the mid-1990s, tribulus terrestris became known in North America after Eastern European Olympic athletes said that taking tribulus helped their performance.
The active compounds in tribulus are called steroidal saponins. Two types, called furostanol glycosides and spirostanol glycosides, appear to be involved with the effects of tribulus. These saponins are found primarily in the leaf.
Why Do People Use Tribulus?
Tribulus is most often used for infertility, erectile dysfunction, and low libido. In the last decade, it has become popular to improve sports performance.
Tribulus has been marketed these conditions because research performed in Bulgaria and Russia indicates that tribulus increases levels of the hormones testosterone (by increasing luteinizing hormone), DHEA, and estrogen. The design of these research studies, however, has been questioned.
A more recent study found that four weeks of tribulus supplements (at 10 to 20 milligrams per kg of body weight daily) had no effect on male sex hormones testosterone, androstenedione, or luteinizing hormone compared to people who did not take tribulus.
1) Erectile Dysfunction
Preliminary animal studies found that tribulus heightened sexual behavior and increased intracavernous pressure. This was attributed to increases in testosterone. There haven’t been any well-designed human studies to confirm these early findings.

DRUG APPROVALS BY DR ANTHONY MELVIN CRASTO
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