Comparison of the effect of sildenafil and apomorphine SL on nocturnal erections in healthy volunteers: A placebo-controlled study

Objective: To compare the effects of sildenafil and sublingual (sl) apomorphine on nocturnal erections. Methods: In a prospective, single-blinded, placebo-controlled at-home study we compared the effect of apomorphine sl and sildenafil on sleep-related erectile activity in 30 healthy potent volunteers (mean age, 26.4 years; range, 23-35 years; Erectile Function domain of the International Index of Erectile Function ≥26), not reporting any subjective sleep abnormality during 4 consecutive nights with rigidity monitoring (NPTR) with the RigiScan™ device. After the first night of adaptation, they were randomized to receive placebo or apomorphine sl 2 mg or sildenafil 50 mg taken at bedtime during the following 3 consecutive nights. Results: Sildenafil increased the mean ± SE number of erections, overall length of erectile events, and the time of erections with rigidity >60% at both tip and base, as compared to placebo. The same parameters were reduced after administration of apomorphine sl. Similar findings were observed with regards to Rigidity Activity Units and Tumescence Activity Units. Conclusions: Our results confirm that sildenafil taken at bedtime might increase nocturnal erectile activity also in young potent men as compared to placebo. Apomorphine sl taken at bedtime seems to have the opposite effect.