A Randomized, Double-Blind, Placebo-Controlled, Parallel Study to Assess the Efficacy and Safety of Once-A-Day Tadalafil in Men with Erectile Dysfunction Who Are Naïve to PDE5 Inhibitors

Introduction. The majority of subjects included in previous tadalafil once-a-day clinical trials were non-naïve to previous phosphodiesterase 5 (PDE5) inhibitors on demand. A study on PDE5 inhibitor naïve subjects was therefore warranted. Aim. To evaluate the efficacy and safety of once-a-day tadalafil in PDE5 inhibitor-naïve men with erectile dysfunction (ED). Main Outcomes Measures. Primary efficacy end points were changes from baseline to end point in the International Index of Erectile Function (IIEF) Erectile Function (EF) domain score and the per-subject proportion of "yes" responses to sexual encounter profile (SEP) question 2 (SEP2) and question 3 (SEP3). Methods. PDE5 inhibitor-naïve men with ED (N=217) were randomized in a 1:2 ratio to receive placebo or tadalafil 5mg once a day for 12 weeks. Enrollment began in January 2009 and the last subject completed in January 2010. Results. At end point, least square mean change from baseline IIEF-EF domain score (7.3 vs. 3.4), SEP2 (23.8% vs. 12.2%) and SEP3 (39.5% vs. 21.5%), was significantly larger for tadalafil vs. placebo (all P