Evaluation of the Efficacy and Safety of Once-a-Day Dosing of Tadalafil 5 mg and 10 mg in the Treatment of Erectile Dysfunction: Results of a Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial

BackgroundErectile dysfunction (ED) is a chronic disease; however, therapy is currently administered as needed with oral phosphodiesterase 5 (PDE5) inhibitors like tadalafil. Because the 17.5-h half-life of tadalafil enables therapeutic plasma levels to be sustained with daily administration, tadalafil is a good candidate for once daily dosing therapy.MethodsThis multicenter, randomized, double-blind, placebo-controlled, parallel-group, 12-week study enrolled 268 men 1:2:2 to placebo, tadalafil 5 mg, and tadalafil 10 mg taken once daily. Primary efficacy measures included changes in the International Index of Erectile Function Erectile Function domain (IIEF EF), Sexual Encounter Profile diary Questions 2 (SEP2: successful penetration), and 3 (SEP3: successful completion of intercourse), and tolerability. Secondary measures included percentage of patients at endpoint who reported improved erectile function (EF), and percentage who reported “no ED” (IIEF EF score 26–30).ResultsFor patients who took placebo, tadalafil 5 mg, and tadalafil 10 mg, changes from baseline to endpoint were, respectively, 0.9, 9.7, and 9.4 for IIEF EF; 11.2, 36.5, and 39.4 for SEP2; and 13.2, 45.5, and 50.1 for SEP3. At endpoint, 28.3%, 84.5%, and 84.6% reported improved erections, and 8.3%, 51.5%, and 50.5% reported “no ED,” respectively. All comparisons between tadalafil and placebo were significant (p < 0.001). Adverse events that occurred in at least 5% of patients were dyspepsia, headache, back pain, upper abdominal pain, and myalgia; nine patients (3.4%) discontinued because of adverse events.ConclusionsOnce-a-day tadalafil 5 mg or 10 mg was well tolerated and significantly improved EF in men with ED.