Clinical utility of phentermine/topiramate (Qsymia™) combination for the treatment of obesity

Qsymia™ (Vivus Inc, Mountain View, CA, USA), a combination of phentermine and delayed-release topiramate, has been available in the US since September 2012 for the treatment of obesity. Phentermine is an anorexigenic agent, which is approved for the short-term treatment of obesity, while topiramate is approved for nonweight loss indications – seizure disorders and migraine prophylaxis. The amount of weight loss achieved with combination therapy is of a greater magnitude than what could be achieved with either agent alone. Adverse events that occur with the combination therapy are in line with the known side effect profiles of the constituent drugs; teratogenicity, a slight increase in heart rate, psychiatric and cognitive adverse effects, and metabolic acidosis are concerns.