Objective: To evaluate, in a randomized, double-blind, placebo-controlled, multicentre trial, the safety and efficacy of on-demand tadalafil (an oral phosphodiesterase type-5 inhibitor approved in many countries for treating erectile dysfunction, ED) in a Western European population of men with mild-to-severe ED.
Patients and methods: Patients were randomized according to baseline severity of ED in a ratio of 3 : 1 to receive either tadalafil 20 mg or placebo for 12 weeks. Primary efficacy endpoints were mean changes from baseline to endpoint (12 weeks) in the erectile function (EF) domain of the International Index of Erectile Function (IIEF) and percentages of 'Yes' responses to Sexual Encounter Profile (SEP) diary Question 2 ('Were you able to insert your penis into your partner's vagina?') and Question 3 ('Did your erection last long enough for you to have successful intercourse?'). Secondary endpoints included mean changes from baseline to endpoint in IIEF Intercourse Satisfaction and Overall Satisfaction domains, selected questions of the IIEF, and the percentage of 'Yes' responses to Global Assessment Questions (GAQ) at the last visit. Other analyses included the percentage of patients in each treatment group at endpoint with IIEF EF domain scores in the normal range (>26), the frequency of intercourse attempts and mean per-patient intercourse success rate at various times after dosing.
Results: The mean age of the patients was 53 years and 80% had a history of ED of > or = 1 year. The mean baseline EF domain score was 13.5, with 40.5% of patients in the severe category. Tadalafil improved mean EF domain scores by 11.1, vs 0.4 for placebo (P < 0.001). In addition, 73.9% of sexual intercourse attempts were successful (SEP-Q3) in tadalafil-treated patients, compared with 29.9% in placebo-treated patients during the period after baseline (P < 0.001). Tadalafil significantly improved the mean IIEF intercourse satisfaction (5.1, tadalafil; 1.1, placebo) and overall satisfaction domain scores (3.9, tadalafil; 0.5, placebo), P < 0.001. GAQs used to assess the overall effect of the treatment indicated that tadalafil was superior to placebo (P < 0.001) in improving erections (82.1%, tadalafil; 23.1%, placebo) and sexual activity (78.6% and 17.3%). The most common treatment-emergent adverse events more frequent (>2%) with tadalafil than placebo were headache, dyspepsia, flushing, back pain, pain in limb and myalgia. These adverse events were mostly mild to moderate.
Conclusions: Tadalafil improved erectile function and was well tolerated when taken by men from Western Europe with mild-to-severe ED.