A randomized double-blind placebo-controlled study of the long-term efficacy and safety of diethylpropion in the treatment of obese subjects

OBJECTIVE

To evaluate the efficacy of diethylpropion on a long-term basis, with emphasis in cardiovascular and psychiatric safety aspects.

DESIGN

Randomized, double-blind, placebo-controlled trial.

MEASUREMENTS

Following a 2-week screening period, 69 obese healthy adults received a hypocaloric diet and were randomized to diethylpropion 50 mg BID (n=37) or placebo (n=32) for 6 months. After this period, all participants received diethylpropion in an open-label extension for an additional 6 months. The primary outcome was percentage change in body weight. Electrocardiogram (ECG), echocardiography and clinical chemistry were performed at baseline and every 6 months. Psychiatric evaluation and application of Hamilton rating scales for depression and anxiety were also performed by experienced psychiatrists at baseline and every 3 months.

RESULTS

After 6 months, the diethylpropion group lost an average of 9.8% (s.d. 6.9%) of initial body weight vs 3.2% (3.7%) in the placebo group (P<0.0001). From baseline to month 12, the mean weight loss produced by diethylpropion was 10.6% (8.3%). Participants in the placebo group who were switched to diethylpropion after 6 months lost an average of 7.0% (7.7%) of initial body weight. The difference between groups at month 12 was not significant (P=0.07). No differences in blood pressure, pulse rate, ECG and psychiatric evaluation were observed. Dry mouth and insomnia were the most frequent adverse events.

CONCLUSION

Diethylpropion plus diet produced sustained and clinically significant weight loss over 1 year. It seems to be safe in relation to cardiovascular and psychiatric aspects in a well-selected population.