Special Communication |

The New Weight-Loss Drugs, Lorcaserin and Phentermine-Topiramate:  Slim Pickings?

Steven Woloshin, MD, MS1; Lisa M. Schwartz, MD, MS1
[+] Author Affiliations
1The Center for Medicine and the Media, Dartmouth Institute for Health Policy and Clinical Practice, Lebanon, New Hampshire
JAMA Intern Med. 2014;174(4):615-619. doi:10.1001/jamainternmed.2013.14629.
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In 2012, the US Food and Drug Administration approved 2 drugs for long-term weight loss: lorcaserin hydrochloride (Belviq; Eisai Inc) and phentermine-topiramate (Qysmia; Vivus Inc). The approvals were based on 1-year trials showing that on top of recommendations to follow a calorie-restricted diet and to increase exercise, patients randomized to either drug lost more weight than patients randomized to placebo (3% [95% CI, 3%-4%] more weight lost with lorcaserin; 7% [95% CI, 3%-4%] more with phentermine /topiramate). The drugs have been associated with serious harms: Both drugs’ labels include warnings about memory, attention, or language problems and depression; for lorcaserin, the label also warns of valvular heart disease and euphoria; and for phentermine-topiramate, the label warns of metabolic acidosis, increased heart rate, anxiety, insomnia, and elevated creatinine levels. Neither medication is marketed in Europe because of safety concerns. The manufacturer withdrew its application for lorcaserin in Europe after the European Medicines Agency (EMA) said approval was unlikely, and the EMA rejected phentermine-topiramate. In the United States, the required postmarketing safety trials are behind schedule. Until there is more convincing evidence about the cardiovascular safety of these drugs, physicians and patients should approach them cautiously. Patients who do not lose at least 5% of their body weight within 12 weeks of starting to take either drug should stop taking it, as stated in the prescribing information.

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Figure 1.
Drug Facts Box for Phentermine-Topiramate (Qsymia; Vivus Inc)

The data for the benefits and harms of phentermine-topiramate7 are the pooled results of the 2 phase 3 trials. Absolute differences (95% CIs) are reported for the maintenance dose (7.5 mg of phentermine/46 mg of topiramate daily) minus placebo. BMI is calculated as weight in kilograms divided by height in meters squared; HCO3−, bicarbonate; qd, daily.

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Figure 2.
Drug Facts Box for Lorcaserin Hydrochloride (Belviq; Eisai Inc)

The data for the benefits and harms of lorcaserin6 are the pooled results of the 2 general population phase 3 trials. The third phase 3 trial not shown here included 499 people with diabetes. BMI is calculated as weight in kilograms divided by height in meters squared; bid indicates twice daily. This drug facts box was the basis of the one previously published in Consumer Reports8 and is reproduced here with permission.

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