Efficacy and Safety of Tadalafil 20 mg on Demand vs. Tadalafil 5 mg Once-a-Day in the Treatment of Post-Radiotherapy Erectile Dysfunction in Prostate Cancer Men: A Randomized Phase II Trial

Introduction. The role of phosphodiesterase type 5 inhibitors in the treatment of post-radiotherapy erectile dysfunction (ED) has not been extensively investigated. Aim. To compare the efficacy and safety of on-demand 20-mg tadalafil (arm A) with the newly released tadalafil 5-mg once-a-day dosing (arm B) in patients with ED following radiotherapy for prostate cancer (PC). Methods. Randomized study to receive on-demand 20-mg or once-a-day 5-mg tadalafil for 12 weeks. Main Outcome Measures. Changes in the International Index of Erectile Function (IIEF) domain scores and Sexual Encounter Profile (SEP) question 2 and 3 positive response rates. Results. Fifty-two out of 86 screened patients were randomized. Forty-four patients were evaluable for efficacy. A significant improvement in all domains of the IIEF was observed in both arms (P = 0.0001) with mean erectile function domain scores values of 25 and 27.1 for the 20-mg and 5-mg tadalafil, respectively (P = 0.19). SEP 2 and 3 positive response rates increased from 0% in both arms at baseline to 81% and 70% in the 20-mg arm and 90% and 73% in the 5-mg arm, respectively, at the end of treatment (P = 0.27). End of treatment global efficacy question positive answers were 86% in the 20-mg arm and 95% in the 5-mg arm (P = 0.27). Higher treatment compliance was shown in arm B (100%) as compared with arm A (86%). There was a nonstatistically significant trend toward fewer side effects in favor of the 5-mg daily dose arm. Conclusions. In the study population, both tadalafil formulations generated significantly high response rates according to the outcome measures and were well tolerated. The once-a-day 5-mg dosing showed higher compliance and marginally reduced side effects, thus making it an attractive alternative to on-demand therapy for ED in post-radiotherapy PC patients. Ricardi U, Gontero P, Ciammella P, Badellino S, Valentino F, Munoz F, Guarneri A, Rondi N, Moretto F, Filippi AR, Ragona R, and Tizzani A. Efficacy and safety of tadalafil 20 mg on demand vs. tadalafil 5 mg once-a-day in the treatment of post-radiotherapy erectile dysfunction in prostate cancer men: A randomized phase H trial. J Sex Med 2010;7:2851-2859.