Clinical Question: Is rimonabant (Acomplia, not yet approved by the U.S. Food and Drug Administration) effective for reducing weight in obese or overweight patients?

Setting: Outpatient (specialty)

Study Design: Randomized controlled trial (double-blinded)

Allocation: Uncertain

Synopsis: Rimonabant is a selective cannabinoid-1 receptor blocker that reduces appetite and may promote weight loss in patients who are obese or overweight. The investigators enrolled 3,500 overweight (i.e., body mass index [BMI] of greater than 27 kg per m²) and obese (i.e., BMI of 30 kg per m² or greater) adults from 64 U.S. and Canadian clinical research centers. After a four-week period during which all patients received placebo plus prescribed diet, compliant patients (87 percent) randomly received (uncertain allocation concealment) 20 mg rimonabant per day, 5 mg rimonabant per day, or placebo.

During the second year of the study, patients treated with rimonabant were rerandomized to receive placebo or continue to take the same rimonabant dosage. All patients were placed on a 600 kcal per day deficit diet. The authors do not specify whether outcomes were measured by individuals blinded to the treatment group assignment.

At one year, slightly more than one half of the initial patients completed the study protocol; the rest withdrew because of lack of effectiveness, adverse events, poor compliance, or patient request. Using modified intention-to-treat analysis (including only patients who took at least one dose), patients in the 20 mg rimonabant group lost significantly more weight than those receiving placebo (loss of 13.9 lb [6.3 kg] versus loss of 3.5 lb [1.6 kg], respectively); overall difference = 10.4 lb (4.7 kg).The percentage of patients achieving a clinically relevant (i.e., 10 percent or greater) weight loss was 25.2 percent for patients receiving 20 mg rimonabant and 8.5 percent for patients in the placebo group (number needed to treat for one year = 17); the difference between 5 mg rimonabant and placebo was not significant. Patients switching from the 20 mg rimonabant group to the placebo group during year 2 experienced weight gain, whereas those who continued to take 20 mg rimonabant did not.

Bottom Line: Rimonabant is minimally effective in obese or overweight patients for achieving sustained weight loss. Less than one half of the patients initially enrolled in this study completed the protocol at one year. Of those remaining in the study, one fourth lost a clinically significant amount of weight, and, as with other weight loss drugs, the patients who stopped taking the medicine after one year regained the weight. (Level of Evidence: 1b–)