[International study of the effect of dexfenfluramine in obesity (ISIS): 6 months' results].

International study of the effect of dexfenfluramine in obesity (ISIS): 6 months results. ISIS is a multicentre therapeutic trial of the "intention to treat" type organized to test the effectiveness and side-effects of dexfenfluramine combined with diet in the treatment of obesity. This was a randomized, double-blind drug versus placebo study programmed for a one-year period. Eight hundred and twenty-two obese patients were included. Dexfenfluramine was administered in doses of 15 mg b.d. The intermediate results after 6 months of treatment are presented. Significant differences were observed between the dexfenfluramine group (n = 404) and the placebo group (n = 418). In the treated group: 1) the drug withdrawal rate was lower, mainly due to a greater number of patients in the placebo group dissatisfied with their weight loss; 2) about twice as many patients achieved an important loss of weight in terms of percentage of the initial weight or overweight; 3) the cumulative loss of weight was greater; 4) there was a higher incidence of transient side-effects, such as fatigue, diarrhoea, dry mouth, polyuria and drowsiness. These results suggest that dexfenfluramine will be suitable for a more prolonged treatment of obese patients, in addition to diet.