The FDA today approved Qsymia (phentermine and topiramate extended-release) as an addition to a reduced-calorie diet and exercise for chronic weight management.
Qsymia is approved for use in adults with a body mass index (BMI) of 30 or greater (obese) or adults with a BMI of 27 or greater (overweight) who have at least one weight-related condition such as high blood pressure (hypertension), type II diabetes, or high cholesterol. BMI, which measures body fat based on an individual’s weight and height, is used to define the obesity and overweight categories.
Qsymia offers a combination of two FDA-approved drugs, phentermine and topiramate, in an extended-release formulation. Phentermine is indicated for short-term weight loss in overweight or obese adults who are exercising and are on a reduced calorie diet. Topiramate is indicated to treat certain types of seizures in people who have epilepsy and to prevent migraine headaches.
The recommended daily dose of Qsymia contains 7.5 mg of phentermine and 46 mg of topiramate extended-release. Qsymia is also available in a higher dose (15 mg phentermine and 92 mg topiramate extended-release) for selected patients.
The safety and efficacy of Qsymia were evaluated in two randomized, placebo-controlled trials that included approximately 3,700 obese and overweight patients with and without significant weight-related conditions treated for one year. All patients received lifestyle modification that consisted of a reduced calorie diet and regular physical activity.
Results from the two trials show than after one year of treatment with the recommended and highest daily dose of Qsymia patients had an average weight loss of 6.7% and 8.9%, respectively, over treatment with placebo. Approximately 62% and 69% of patients lost at least 5% of their body weight with the recommended dose and highest dose of Qsymia, respectively, compared without about 20% of patients treated with placebo.
Patients who failed to lose at least 3% of their body weight by week 12 of treatment were unlikely to achieve and sustain weight loss with continued treatment at this dose. Therefore, response to therapy with the recommended daily dose of Qsymia should be evaluated by 12 weeks to determine, based on the amount of weight loss, whether to discontinue Qsymia or increase to a higher dose. If after 12 weeks on the higher dose a patient does not lose at least 5% of their body weight, the drug should be discontinued, as these patients are unlikely to achieve meaningful weight loss with continued treatment.
Use of Qsymia during pregnancy is not approved because it can cause harm to the fetus. Data shows than a fetus exposed to topiramate, a component of Qsymia, in the first trimester of pregnancy has an increased risk of oral clefts (cleft lip with or without cleft palate). Females of reproductive potential must ensure they’re not pregnant when starting therapy with Qsymia or become pregnant while taking the drug. Females of reproductive potential should have a negative pregnancy test before starting Qsymia and every month while using the drug and should use effective contraception consistently while taking Qsymia.
Qsymia must also not be used in patients with glaucoma or hyperthyroidism. Qsymia can increase heart rate, and its effect on heart rate in patients at high risk for heart attack or stroke is not really known. Therefore, its use in patients with recent (within the last 6 months) or unstable heart disease or stroke is not recommended. Regular monitoring of heart rate is recommended for all patients taking Qsymia, especially when starting Qsymia or increasing the dose.
Qsymia was approved by the FDA with a Risk Evaluation and Mitigation Strategy (REMS), which consists of a Medication Guide advising patients about important safety information and elements to assure safe use that include prescribed training and pharmacy certification. The purpose of the REMS is to educate prescribers and their patients about the increased risk of birth defects associated with first trimester exposure to Qsymia, the need for pregnancy prevention, and the need to discontinue therapy if pregnancy occurs. Qsymia will only be dispensed through specially certified pharmacies.
Vivus Inc. will be required to conduct 10 postmarketing requirements, including a long-term cardiovascular outcomes trial to assess the effect of Qsymia on the risk for major adverse cardiac events such as heart attack and stroke.
The most common side effects of Qsymia are tingling of hands and feet (paresthesia), dizziness, altered taste sensation, insomnia, constipation, and dry mouth.
Qsymia is marketed by Vivus Inc. in Mountain View, Calif.