ORAL SILDENAFIL IN THE TREATMENT OF ERECTILE DYSFUNCTION

Background. Sildenafil is a potent inhibitor of cyclic guanosine monop hosphate in the corpus cavernosum and therefore increases the penile r esponse to sexual stimulation. We evaluated the efficacy and safety of sildenafil, administered as needed in two sequential double-blind stu dies of men with erectile dysfunction of organic, psychogenic, or mixe d causes. Methods. In a 24-week dose-response study, 532 men were trea ted with oral sildenafil (25, 50, or 100 mg) or placebo. In a 12-week, flexible dose-escalation study, 329 different men were treated with s ildenafil or placebo, with dose escalation to 100 mg based on efficacy and tolerance. After this dose-escalation study, 225 of the 329 men e ntered a 32-week, open-label extension study. We assessed efficacy acc ording to the International Index of Erectile Function, a patient log, and a global-efficacy question. Results. In the dose-response study, increasing doses of sildenafil were associated with improved erectile function (P values for increases in scores for questions about achievi ng and maintaining erections were < 0.001). For the men receiving 100 mg of sildenafil, the mean score for the question about achieving erec tions was 100 percent higher after treatment than at base line (4.0 vs . 2.0 of a possible score of 5.) In the last four weeks of treatment i n the dose-escalation study, 69 percent of all attempts at sexual inte rcourse were successful for the mean receiving sildenafil, as compared with 22 percent for those receiving placebo (P < 0.001). The mean num bers of successful attempts per month were 5.9 for the men receiving s ildenafil and 1.5 for those receiving placebo (P < 0.001). Headache, f lushing, and dyspepsia were the most common adverse effects in the dos e-escalation study, occurring in 6 percent to 18 percent of the men. N inety-two percent of the men completed the 32-week extension study.Con clusions. Oral sildenafil is an effective, well-tolerated treatment fo r men with erectile dysfunction. (C) 1998, Massachusetts Medical Socie ty.