Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II — VialBase Research

Summary

Early clinical study demonstrating that Melanotan II (the parent melanocortin peptide from which PT-141/bremelanotide was derived) induces penile erection and increases sexual motivation in men. This foundational study established the melanocortin system as a target for sexual dysfunction treatment and led to the development of PT-141.

Key Findings

• Subcutaneous Melanotan II induced erections in 9 of 10 male subjects
• Erectile response was dose-dependent
• Sexual motivation/desire increased independent of visual erotic stimuli
• Effects mediated through central melanocortin receptor activation (not peripheral vasodilation)
• Side effects included nausea, facial flushing, and yawning (stretching)
• Led directly to development of bremelanotide (PT-141) as a selective derivative

Methodology

Small clinical study in 10 healthy male volunteers. Subcutaneous Melanotan II at varying doses. Erectile response assessed via RigiScan monitoring. Sexual motivation assessed via questionnaire. Side effects and vital signs monitored.

Limitations

• Very small sample size (n=10)
• Melanotan II, not PT-141 specifically — different selectivity profile
• Healthy volunteers, not ED patients
• No placebo control in this phase
• Melanotan II has broader melanocortin activity (tanning, appetite effects) than PT-141

Relevance to Content

The origin story for PT-141. Content can trace the lineage: melanocortin research → Melanotan II → discovering sexual function effects → developing PT-141 (bremelanotide) as a targeted derivative. Also important for Melanotan II content, as this study documented the sexual side effects that led to PT-141’s development.

See Also

• Parent compound: PT-141
• Related compound: Melanotan-II