Melanotan-II Triggered Erections in Men With Psychogenic Erectile Dysfunction

Double-blind, placebo-controlled crossover study with 10 men diagnosed with psychogenic erectile dysfunction (no organic cause). Each subject received both Melanotan-II (0.025 mg/kg) and placebo subcutaneously in randomized order. Erections were measured objectively using real-time RigiScan monitoring over a 6-hour period, recording presence, duration, and rigidity.

This was one of the earliest controlled studies demonstrating that a peptide acting through the melanocortin system in the brain — rather than directly on blood vessels like Viagra — could trigger erections. It proved that sexual arousal could be initiated centrally through peptide signaling, opening an entirely new pathway for treating erectile dysfunction. This research ultimately contributed to the development of bremelanotide (Vyleesi), which was FDA-approved in 2019 for hypoactive sexual desire disorder.

This 1998 study was a landmark in sexual medicine. It demonstrated that the melanocortin pathway — a brain-based system primarily associated with skin pigmentation — could be leveraged to treat sexual dysfunction. This central nervous system approach was fundamentally different from Viagra's peripheral vascular mechanism. The research paved the way for bremelanotide (Vyleesi), a refined melanocortin agonist FDA-approved in 2019 for female hypoactive sexual desire disorder.

Very small sample size (n=10). Only men with psychogenic (non-organic) erectile dysfunction were included, so results may not apply to men with vascular or neurogenic causes. The crossover design helps control for individual variation but the small numbers limit statistical power. Melanotan-II is not FDA-approved and has significant safety concerns beyond what this short study captured.