Phentermine/topiramate: Difference between revisions

| verifiedrevid = 414490995

| type = combo

| class1 = [[appetite suppressant]]/[[stimulant]] of the [[amphetamine]] and [[phenethylamine]] class

| class2 = [[anticonvulsant]]

| tradename =

| pregnancy_US = <!-- A / B / C / D / X -->

| legal_US = <!-- OTC / Rx-only / Schedule I, II, III, IV, V -->

| legal_status = experimental, yet has been submitted to the FDA for approval

| routes_of_administration =

| CAS_number =

| ATC_prefix = none

| ATC_suffix =

| PubChem =

| DrugBank_Ref = {{drugbankcite|correct|drugbank}}

| DrugBank =

The combination of the [[pharmaceutical drug|drugs]] '''[[phentermine]] and [[topiramate]]''' (trade name '''Qnexa''') is an investigational medication for the treatment of [[obesity]] and related conditions such as [[type 2 diabetes]] and has been found to lower blood pressure and cholesterol.<ref>[http://ir.vivus.com/releasedetail.cfm?ReleaseID=353074 Vivus Inc.],</ref> Qnexa is being developed by [[Vivus]], a California pharmaceutical company.<ref>[http://www.vivus.com/pipeline/qnexa-obesity Vivus Inc.]</ref> [[Phentermine]] is an [[appetite suppressant]] and [[stimulant]] of the [[amphetamine]] and [[phenethylamine]] class. [[Topiramate]] is an [[anticonvulsant]] that has weight loss side effects.

Qnexa is currently not approved for use in the United States. It was rejected by regulators in the United States Food and Drug Administration after a panel found that tests showed that it was associated with a number of dangerous side effects, including suicidal thoughts, heart palpitations, memory lapses and birth defects.<ref>{{cite web |url=http://www.msnbc.msn.com/id/39905030/ns/health-diet_and_nutrition/ |title=FDA rejects second weight-loss drug in a week |date=10/29/2010 5:06:32 AM ET |publisher=msnbc.com news services |accessdate=29 October 2010}}</ref>

Clinical studies have shown weight loss under treatment with Qnexa. The phase 3, 56-week EQUIP study showed that the average weight loss of 14.7% (37&nbsp;lbs) was achieved by obese patients treated with Qnexa.<ref>[http://www.news-medical.net/news/20090909/VIVUS-Phase-3-studies-find-Qnexa-effective-in-tackling-obesity.aspx Vivus Phase 3 studies find Qnexa effective in tackling obesity]</ref> The following doses of phentermine IR and topiramate CR where used in Phase 3 testing:

*Full strength formula: 15&nbsp;mg of phentermine IR (instant-release) and 92&nbsp;mg of topiramate CR (controlled-release)

*Mid strength formula: 7.5&nbsp;mg phentermine IR and 46&nbsp;mg topiramate CR

*Low strength formula: 3.75&nbsp;mg phentermine IR and 23&nbsp;mg topiramate CR

The main side effects reported during testing phases were dry mouth, a tingling in the fingers and toes, and constipation.<ref>[http://www.nytimes.com/2009/09/10/business/10biotech.html?hpw Vivus Says Qnexa, a Diet Drug, Did Well in Trials]</ref> On December 28, 2009 a [[new drug application]] (NDA) was submitted to the FDA for approval<ref>[http://www.prnewswire.com/news-releases/vivus-submits-qnexar-new-drug-application-to-the-fda-for-the-treatment-of-obesity-80258207.html VIVUS Submits Qnexa(R) New Drug Application to the FDA for the Treatment of Obesity]</ref> and on March 1, 2010, Vivus announced that the agency accepted the NDA.<ref>[http://www.marketwatch.com/story/fda-accepts-vivus-application-for-obesity-drug-2010-03-01 FDA accepts Vivus application for obesity drug]</ref> The target date for the FDA to complete its review of the Qnexa NDA is October 28, 2010.<ref>[http://ir.vivus.com/releasedetail.cfm?ReleaseID=447799 VIVUS Announces FDA Acceptance of Qnexa(R) New Drug Application for Treatment of Obesity]</ref> The FDA's Endocrinologic and Metabolic Drugs Advisory Committee is tentatively scheduled to review Vivus' Qnexa on July 15, 2010. It is expected that this may provide an indication on whether it is approved or not.<ref>[http://www.drugs.com/nda/qnexa_100326.html VIVUS Announces Date of FDA Advisory Committee Review of Qnexa for the Treatment of Obesity]</ref>

Qnexa is also in phase 2 clinical development for the treatment of type 2 diabetes and [[obstructive sleep apnea]] (OSA). A phase 2 safety and efficacy study evaluating Qnexa in patients with OSA showed that patients who took Qnexa had a 69 percent reduction in sleep apnea events and lost more weight than those who took placebo.<ref>[http://www.reuters.com/article/idUSN0616752520100107 Vivus' Qnexa improves sleep apnea in small trial]</ref>

Vivus currently has four U.S. patents covering Qnexa. These patents are related to the product and methods of using the drug in various therapeutic applications.<ref>[http://ir.vivus.com/releasedetail.cfm?ReleaseID=449907 VIVUS Announces the Issuances of Three Additional Qnexa(R) Patents]</ref>

Further research data released indicates that Qnexa lowers blood pressure. Dr. Suzanne Oparil of the University of Alabama at Birmingham stated “The higher the dose, the more weight loss and the more blood pressure went down” presented at the American Society of Hypertension’s 25th annual meeting in New York.<ref>[http://www.reuters.com/article/idUSTRE64355C20100504 Qnexa weight loss drug lowers blood pressure: study]</ref>

In January 2011, the [[Food and Drug Administration]] expressed concerns about the potential for Qnexa to cause birth defects and has asked Vivus to examine this possibility before the drug can be approved.<ref>[http://www.businessweek.com/ap/financialnews/D9KSPDA00.htm Vivus says FDA asks about Qnexa birth defect link], ''Business Week'', January 21, 2011</ref>

==References==

[[Category:Combination drugs]]