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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


Sebastian Sorsaburu, MD, Lilly Research Laboratories, Eli Lilly, Indianapolis, IN 46285, USA. Tel: 317-651-8211; Fax: 317-433-4901; E-mail:


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 5 mg 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 < 0.001). The most common adverse events (AEs) in tadalafil-treated subjects were back pain, nasopharyngitis, dyspepsia, headache, and myalgia. Four subjects (2.7%) in the tadalafil group and one subject (1.4%) in the placebo group discontinued because of AEs.

Conclusions.  In PDE5 inhibitor-naïve men, tadalafil once a day significantly improved EF compared with placebo. Safety results were consistent with previous tadalafil once-a-day clinical trials. Montorsi F, Aversa A, Moncada I, Perimenis P, Porst H, Barker C, Shane MA, and Sorsaburu S. 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. J Sex Med 2011;8:2617–2624.