PMID-9679884 – Melanotan II Initiates Erections in Psychogenic ED
Wessells H, Fuciarelli K, Hansen J, Hadley ME, Hruby VJ, Dorr R, Levine N. "Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study," J Urol, 1998;160(2):389-393.
Quick Reference
| Property | Value |
|---|---|
| PMID | 9679884 |
| DOI | — |
| Year | 1998 |
| Journal | The Journal of Urology |
| Study Type | RCT |
| Evidence Level | II |
| Sample | n=10 men with psychogenic erectile dysfunction |
| Peptide(s) Studied | Melanotan II |
Key Findings
- Seminal double-blind, placebo-controlled crossover study of subcutaneous Melanotan II in men with psychogenic ED
- 8 out of 10 men developed clinically meaningful erections after MT-II administration
- Mean penile rigidity exceeded 80% for a mean duration of 38 minutes with MT-II
- Placebo group: mean rigidity duration of only 3 minutes (p=0.0045)
- Erections occurred without visual or physical sexual stimulation — purely centrally mediated
- Demonstrated that melanocortin receptor activation in the CNS can directly initiate erectile response
- First controlled human evidence for the erectogenic properties of melanocortin agonists
- Side effects included mild nausea, yawning, and stretching
Study Design
Double-blind, placebo-controlled, crossover study. 10 men with documented psychogenic erectile dysfunction received subcutaneous Melanotan II (0.025 mg/kg) or placebo on separate visits. Penile rigidity and tumescence were monitored continuously using RigiScan. No sexual stimulation was provided during monitoring periods.
Limitations
- Very small sample size (n=10)
- Only psychogenic ED studied; organic ED not represented
- Single-dose evaluation; no repeated dosing data
- RigiScan monitoring in a clinical setting may not reflect real-world sexual function
- Nausea reported by most subjects, which could limit clinical utility
Clinical Relevance
This 1998 study is historically foundational — it is the first controlled demonstration that a melanocortin peptide can initiate erections in humans via central pathways without sexual stimulation. This discovery led directly to the development of bremelanotide (PT-141). The 80% penile rigidity sustained for 38 minutes is a clinically robust effect. For practitioners, it establishes Melanotan II's erectogenic mechanism and explains the pharmacological basis for the entire melanocortin-based sexual health therapeutic class.
Related
#research #RCT #evidence-level-II