Onset of Efficacy of Tadalafil Once Daily in Men With Erectile Dysfunction: A Randomized, Double-Blind, Placebo Controlled Trial

Purpose: We evaluated the efficacy onset and safety of tadalafil 2.5 and 5 mg once daily for 14 days compared with placebo in men with erectile dysfunction. Materials and Methods: In this randomized, double-blind, placebo controlled, parallel group study we randomized 372 men after a 4-week run-in period to receive placebo, or tadalafil 2.5 or 5 mg once daily for 14 days, followed by a 14-day open label extension period of tadalafil 5 mg once daily. Primary analysis focused on the cumulative percent of men with a successful intercourse attempt during the first 4 days of treatment. On secondary analysis we evaluated the percent of successful attempts during the study. The Sexual Encounter Profile diary question 3 was used to assess efficacy. Safety was assessed by monitoring adverse events and vital signs. Results: Significantly more men in the tadalafil 5 mg group achieved successful intercourse, as indicated by a yes response to diary question 3, than those on placebo by day 2 (48.6% vs 36.6%, p < 0.025). The tadalafil 2.5 mg group did not separate from the placebo group on primary analysis. Secondary analysis showed that men on tadalafil 2.5 mg achieved a significantly higher percent of successful intercourse attempts than those on placebo by day 3 (35.5% vs 27.2%, p < 0.025). All groups further improved during the open label extension period. Tadalafil was well tolerated. Conclusions: This prospective trial shows the onset of efficacy of tadalafil 2.5 and 5 mg once daily within a few days of initiating therapy.