Objective: To examine the safety and efficacy of topiramate (TPM) for maintaining weight following a low-calorie diet.
Research Methods and Procedures: Obese subjects (30 ≤ BMI < 50 kg/m2) 18 to 75 years old received a low-calorie diet for 8 weeks. Those who lost ≥8% of their initial weight received TPM (96 or 192 mg/d) or placebo; all were on a lifestyle modification plan. Sixty weeks of medication were planned. Sponsor ended study early to develop a new controlled-release formulation with the potential to enhance tolerability and simplify dosing in this patient population. Efficacy was analyzed in subjects who completed 44 weeks of treatment before study termination.
Results: Of the 701 subjects enrolled, 80% lost ≥8% of their initial body weight and were randomized; 293 were analyzed for efficacy. Most withdrawals were due to premature termination of the study. Subjects receiving TPM lost 15.4% (96 mg/d) and 16.5% (192 mg/d) of their enrollment weight by week 44, compared with 8.9% in the placebo group (p < 0.001). Subjects on TPM continued to lose weight after the run-in, whereas those on placebo regained weight. Significantly more TPM subjects lost 5%, 10%, or 15% of their randomization weight than placebo. Most adverse events were related to the central nervous system.
Discussion: During a treatment period of 44 weeks, TPM was generally well tolerated, and subjects maintained weight loss initially achieved by a low-calorie diet—and produced additional clinically significant weight loss beyond that achieved by a low-calorie diet.