Long-term weight control study I (weeks 0 to 34): The enhancement of behavior modification, caloric restriction, and exercise by fenfluramine plus phentermine versus placebo

To investigate the value of anorexiant medications as an adjunct to other forms of weight control therapy, we studied 121 people in a 34-week, double-blind clinical trial of 60 mg extended-release fenfluramine plus 15 mg phentermine resin versus placebo added to behavior modification, caloric restriction, and exercise. Participants weighed 130% to 180% (154% ± 1.2%, mean ± SEM) of ideal body weight (1983 Metropolitan Life tables) and were in good health. By week 34, participants receiving active medication lost an average of 14.2 ± 0.9 kg, or 15.9% ± 0.9% of initial weight (n = 58), versus a loss of 4.6 ± 0.8 kg or 4.9% ± 0.9% of initial weight by subjects taking placebo (n = 54; p < 0.001). On visual analog scales, participants rated fenfluramine plus phentermine as more helpful than placebo (50.3 ± 0.5 versus 20.3 ± 0.3) and not bothersome (fenfluramine plus phentermine, 17.4 ± 0.3 versus 13.5 ± 0.2). Blood pressure decreased and pulse remained unchanged in both groups. Dry mouth was the most common adverse effect in subjects receiving fenfluramine plus phentermine; all adverse effects decreased after 4 weeks. Only nine participants left the study in the first 34 weeks. Two subjects from each group left the study as a result of adverse effects. Overall, fenfluramine plus phentermine used in conjunction with behavior modification, caloric restriction, and exercise aided weight loss and continued to be efficacious for 34 weeks.