Phentermine/topiramate, sold under the brand name Qsymia, is a combination drug of phentermine and topiramate used to treat obesity. It is used together with dietary changes and exercise. If less than 3% weight loss is seen after 3 months it is recommended the medication be stopped. The weight loss is modest. Effects on heart related health problems or death is unclear.Common side effects include tingling, dizziness, trouble sleeping, and constipation. Serious side effects may include suicide, abuse. Use is not recommended during pregnancy. Phentermine is a stimulant and appetite suppressant. Topiramate is an anticonvulsant that has weight loss side effects. The exact mechanism of action for both drugs is unknown.Phentermine/topiramate was approved for medical use in the United States in 2012. Approval was denied in Europe, due to concerns regarding safety. Medical uses
In clinical trials, people treated with the highest dose of phentermine/topiramate ER in combination with a program of diet and exercise lost 10% to 11% of their body weight compared to 1% to 2% for those who received placebo. In addition, 62% to 70% of subjects receiving the recommended dose or top dose of phentermine/topiramate ER achieved ≥5% weight reduction by week 56 (ITT-LOCF) compared to 17% to 21% of those receiving a placebo.A Cochrane review on the long-term effects of weight-reducing drugs on people with hypertension found that phentermine/topiramate reduced body weight (when compared to orlistat, and naltrexone/bupropion) and also reduced blood pressure.
Contraindications
Phentermine/topiramate ER is contraindicated in pregnancy, glaucoma, hyperthyroidism, during or within 14 days of taking monoamine oxidase inhibitors, and in patients with hypersensitivity or idiosyncrasy to sympathomimetic amines. Phentermine/topiramate ER can cause an increase in resting heart rate. History
Phentermine and topiramate was developed by Vivus, a California pharmaceutical company. In December 2009 VIVUS, Inc. submitted a new drug application (NDA) to the FDA and on March 1, 2010, VIVUS, Inc. announced that the FDA accepted the NDA for review. In October 2010, the FDA announced its decision to not approve phentermine/topiramate ER in its current form and issued a Complete Response Letter to VIVUS due to lack of long-term data and concerns about side effects including elevated heart rate, major adverse cardiovascular events, and birth defects.The FDA expressed concerns about the potential for phentermine/topiramate ER to cause birth defects and requested that Vivus assess the feasibility of analyzing existing healthcare databases to determine the historical incidence of oral cleft in offspring of women treated with topiramate for migraine prophylaxis (100 mg).In October 2011, VIVUS resubmitted the NDA to the FDA with responses to the issues addressed in the CRL. The FDA accepted the NDA in November 2011.On September 18, 2012, Qsymia became available on the US market. References
External links
"Phentermine mixture with topiramate". Drug Information Portal. U.S. National Library of Medicine.