Sunday Aug 31, 2014 (foodconsumer.org) - A report in JAMA Internal Medicine suggests that physicians should exercise caution when they consider giving their obese patients one of the two weight loss drugs, lorcaserin and phentermine/topiramate, which were approved by the Food and Drug Administration in 2012.

Lorcaserin hydrochloride (Belviq) marketed by Eisai Inc and phentermine-topiramate (Qysmia) made by Vivus Inc are indicated for the long term weight loss.

According to the report, patients who took lorcaserin or phentermine/topiramate lost 3% or 7% more weight, respectively, than those who took placebo in a one-year trial in which patients were also asked to follow a calorie-restricted diet and increase exercise.

Both lorcaserin and phetermine/topiramate "have been associated with serious harms," according to the report.  Both drugs labels indicate that the treatments can affect memory, attention and language and cause depression.  Lorcaserin is also associated with valvular heart disease and euphoria and phentermine-topiramate is linked to metabolic acidosis, increased heart rate, anxiety, insomnia and increased creatinine concentrations.

Because of the safety concerns, the European Medicines Agency (EMA) rejected phentermine-topiramate as a weight loss treatment and said that the approval of lorcaserin as an anti-obesity medication was unlikely, leading to the drug maker withdrawing its application to market the drug in Europe.

The United States has approved the two weight loss medications, but "the required post-marketing safety trials are behind schedule', according to the report authored by S. Woloshin and L.M. Schwarts from Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, New Hampshire. 

The authors caution that physicians and patients should approach the two weight loss drugs cautiously and obese patients who do not lose at least 5% weight within 12 weeks of taking either drug should discontinue the treatment, which is advised in the prescription information.  (David Liu, PHD)

Woloshin S, Schwartz LM.  The new weight-loss drugs, lorcaserin and phentermine-topiramate: slim pickings?  JAMA Intern Med. 2014 Apr;174(4):615-9.