Update on obesity pharmacotherapy.

There are two groups of approved drugs that can be used to manage weight in patients with obesity: medications approved for obesity per se and medications that affect body weight for obese patients who have complications from their obesity and are receiving these medications for chronic disease management. For obesity per se, treatment is with one of the three drugs currently approved for long-term treatment of obesity or one of a few others that can be used for short-term treatment. Among these, orlistat partially blocks intestinal digestion of fat and produces weight loss of 5-8 kg but major limitations are associated gastrointestinal symptoms; lorcaserin, a serotonin-2C agonist with few side effects, produces a mean weight loss of 4-7 kg; and the combination of phentermine and topiramate (extended release) produces a mean weight loss of 8-10 kg, but should only be used after verifying a woman is not pregnant. Failure to lose more than 3% of body weight within 3 months with any of these agents should lead to reevaluation of therapy. The short-term drugs for treating obesity per se are sympathomimetics, with phentermine being most widely used. The second group of drugs is for weight-centric prescribing for patients with a chronic disease such as diabetes, depression, or psychiatric disorders. For each disorder, some drugs produce weight gain, others are weight neutral, but the best choice for these patients is the combination of drugs that treat the underlying condition and also produce weight loss.