About Phentermine and Topiramate Extended-Release (Qsymia)
July 18, 2012
The dramatic increase in overweight/obesity rates in the United States over the past 20 years has resulted in a national health crisis. According to the Centers for Disease Control and Prevention (CDC), about 36 percent of adults (and 17 percent of children and adolescents) in the U.S. are clinically obese. In July 2012, the U.S. Food and Drug Administration (FDA) approved phentermine/topiramate extended-release (Qsymia) to treat overweight/obesity in adults.
Like the recently-approved drug Belviq, Qsymia is approved for people over the age of 18 who have a body mass index (BMI) of 30 or greater, and those with a BMI between 27 and 29 who have a weight-related medical condition like type 2 diabetes or high blood pressure (hypertension). Each of these weight-loss medications is prescribed in combination with lifestyle changes, including a reduced-calorie diet and exercise program. Qsymia is taken once daily and is available in two doses7.5 mg of phentermine and 46 mg of topiramate ER and 15 mg phentermine and 92 mg topiramate ER.
Qsymia and Weight Management
In clinical trials, people who took Qsymia at the lower dose had an average weight loss 6.7 higher than those who took a placebo after one year, and people who took the higher dose of the drug lost an average of 8.9 percent more weight than with a placebo. After one year of treatment, more than 60 percent of people who took either dose of Qsymia lost at least 5 percent of their total body weight, compared to 20 percent of people who took a placebo.
Studies show that people taking Qsymia who do not lose at least 3 percent of their body weight after 3 months of treatment with the drug are unlikely to achieve the desired weight loss at the current dose. In these people, the drug should be discontinued or increased to the higher dose. When treated with the higher dose, the drug should be discontinued if at least 5 percent weight loss is not achieved after 3 months. In these people, Qsymia is not likely to be effective.
Qsymia Warnings and Contraindications
Qsymia must not be used in women who are pregnant or women who may become pregnant. Topiramate (a component of the medication) has been shown to cause birth defects, especially when taken during the first 3 months of pregnancy. Women of childbearing age should have a pregnancy test before starting the medication and every month during weight loss treatment with Qsymia, and should use reliable contraception consistently for as long as they are taking the drug.
People who have glaucoma or hyperthyroidism also should not take Qsymia. Because the medication can increase heart rate in some people, those who are at high risk for heart attack or stroke and those with other heart conditions, such as unstable angina, should talk to their health care provider about the risks of taking Qsymia. During treatment, regular heart rate monitoring is recommended.
Qsymia Side Effects
Common side effects of phentermine/topiramate extended-release (Qsymia) include the following:
- Altered sense of taste
- Dry mouth
- Insomnia (difficulty falling or staying asleep)
- Tingling of the hands and feet (paresthesia)
Additional studies about the long-term effects of Qsymia, including potential cardiovascular risks like heart attack and stroke, are ongoing. If you're considering weight loss medication, talk to your health care provider about the benefits and risks of this drug.