Conclusions:

The US Food and Drug Administration recently approved two drugs for weight loss. Both lorcaserin hydrochloride (Belviq; Eisai Inc.) and phentermine-topiramate (Qysmia; Vivus Inc.) demonstrated greater weight loss over a 1-year period compared to control groups. In addition to the medications, patients followed a low-calorie diet and performed regular exercise. Lorcaserin is a selective 5-HT2C receptor agonist. It is hypothesized that lorcaserin targets receptors in the brain that generate a sense of satiety. Phentermine-topiramate is a combination drug. Phentermine is a sympathomimetic agent, which is an appetite suppressant. Topiramate is an antiepileptic drug, which promotes weight loss; currently, the mechanism of action is not clear.

Both drugs have possible serious adverse effects. Labeling for both lorcaserin and phentermine-topiramate warn of problems with memory, attention, and/or language as well as depression. Additional warnings for lorcaserin include valvular abnormalities, and for phentermine-topiramate, the label warns of metabolic acidosis, increased heart rate, anxiety, insomnia, and elevated creatinine levels. The most common adverse effects for phentermine-topiramate were paresthesias and dry mouth, and for lorcaserin, headache and dizziness. These concerns have led to neither medications being marked in Europe. Currently, the United States requires post-marketing safety trials; however, these trials are behind schedule. It is recommended that for patients who do not lose 5% or more of their body weight in 12 weeks, these drugs should be discontinued.

The authors expressed concerns that these drugs were approved prior to having adequate data on long-term safety including any adverse cardiovascular effects. The authors state that adults who are overweight or obese need effective strategies to lose weight; however, safety of any interventions needs to be considered. Physicians and patients should approach these medications with caution.