We review our experience with Melanotan II, a non-selective melanocortin receptor agonist, in human subjects with erectile dysfunction (ED). Melanotan II was administered to 20 men with psychogenic and organic ED using a double-blind placebo-controlled crossover design. Penile rigidity was monitored for 6 h using RigiScan. Level of sexual desire and side effects were reported with a questionnaire.In the absence of sexual stimulation, Melanotan II led to penile erection in 17 of 20 men. Subjects experienced a mean of 41 min Rigiscan tip rigidity b 80%. Increased sexual desire was reported after 13a19 (68%) doses of Melanotan II vs 4a21 (19%) of placebo (P`0.01). Nausea and yawning were frequently reported side effects due to Melanotan II; at a dose of 0.025 mgakg, 12.9% of subjects had severe nausea.We conclude that Melanotan II is a potent initiator of penile erection in men with erectile dysfunction. Our ®ndings warrant further investigation of melanocortin agonists and antagonists on penile erection.

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