Comparison of Efficacy, Safety, and Tolerability of On-Demand Tadalafil and Daily Dosed Tadalafil for the Treatment of Erectile Dysfunction


Chris McMahon, MD, FACSHP, Australian Centre for Sexual Health, Suite 2-4, 1A Berry Road, St Leonards, Sydney, New South Wales 2065, Australia. Tel: +61 294373906; Fax: +61 299065900; E-mail:


Objective.  To assess and compare the efficacy of on-demand tadalafil and daily tadalafil in the treatment of erectile dysfunction.

Materials and Methods.  A total of 145 men with a mean age of 57.3 years (range 19–82 years) and mild to severe erectile dysfunction of various etiologies were randomized to receive on-demand tadalafil (20 mg) or daily tadalafil (10 mg) taken without food or alcohol restrictions in a trial lasting 26 weeks. The three primary outcome measures were changes from baseline in the erectile function domain of the International Index of Erectile Function (IIEF), the proportion of “yes” responses to questions 2 and 3 of the Sexual Encounter Profile (SEP). Additional efficacy instruments included a Global Assessment Question administered at completion of the study.

Results.  Compared with baseline, on-demand and daily tadalafil enhanced all efficacy outcomes. Patients receiving on-demand tadalafil (20 mg) and daily tadalafil (10 mg) experienced a significant mean improvement of 8.3 and 11.9, respectively, in the erectile function domain of the IIEF from baseline (P < 0.001). The mean change from baseline was significantly higher for daily dosed tadalafil than for on-demand tadalafil (P < 0.05). Sexual intercourse was successfully completed (SEP3) in 69% and 84% of patients taking on-demand tadalafil and daily tadalafil, respectively, compared with 30% at baseline (P < 0.001). Successful completion of sexual intercourse was statistically higher for daily tadalafil than for on-demand tadalafil (P < 0.05). Treatment with on-demand tadalafil or daily tadalafil was well tolerated, and headaches, facial flushing, and dyspepsia were the most frequently observed adverse events.

Conclusion.  Tadalafil was effective and well tolerated in this patient population. Treatment with daily tadalafil was associated with a significantly higher IIEF erectile function domain score and completion of successful intercourse compared with on-demand tadalafil.