Tadalafil in the treatment of erectile dysfunction following bilateral nerve sparing radical retropubic prostatectomy: A randomized, double-blind, placebo controlled trial

Purpose: We evaluated the efficacy and safety of tadalafil 20 mg, taken on demand, in men with erectile dysfunction following bilateral nerve sparing radical retropubic prostatectomy (BNSRRP). Materials and Methods: This randomized, double-blind, placebo controlled multicenter study consisted of a 4-week treatment-free run-in period (baseline) followed by 12 weeks of treatment. A total of 303 men (mean age 60 years) with preoperative normal erectile function who had undergone a BNSRRP 12 to 48 months before study were randomized (2:1) to tadalafil (201) or placebo (102). The 3 co-primary end points were changes from baseline in the International Index of Erectile Function erectile function domain score, and the percentage of positive responses to Sexual Encounter Profile questions 2 (successful penetration) and 3 (successful intercourse). The Global Assessment Question and the Erectile Dysfunction Inventory of Treatment Satisfaction questionnaire were secondary end points. We defined a priori a subgroup of 201 patients reporting evidence of postoperative tumescence, defined as 50% or greater "yes" responses to Sexual Encounter Profile question 1 (ability to achieve at least some erection) during baseline intercourse attempts and stratified randomization based on this criterion. Results: Patients receiving tadalafil reported greater improvement on all primary and secondary end points (p < 0.001) compared to placebo. For all randomized patients and for the subgroup with evidence of postoperative tumescence, the mean International Index of Erectile Function erectile function domain score increased for patients receiving tadalafil (mean +/- SEM 5.3 +/- 0.5 and 5.9 +/- 0.7, respectively, p < 0.001 vs placebo for both). For all randomized patients who received tadalafil, the mean percentage of successful penetration attempts was 54% and the mean percentage of successful intercourse attempts was 41%. For the subgroup with evidence of postoperative tumescence these values were 69% and 52%, respectively. Of all patients randomized to tadalafil 62% and of the subgroup patients randomized to tadalafil 71% reported improved erections. Patients receiving tadalafil reported greater treatment satisfaction on the Erectile Dysfunction Inventory of Treatment Satisfaction than those receiving placebo. Headache (21%), dyspepsia (13%) and myalgia (7%) were the most commonly reported adverse events. Conclusions: Tadalafil 20 mg, taken on-demand, was an efficacious and well tolerated treatment for erectile dysfunction following BNSRRP.