ERECTOGENIC PROPERTIES OF MELANOTAN II IN MEN WITH ORGANIC ERECTILE DYSFUNCTION

Introduction and Objectives

* * Melanotan II (MTII), a superpotent cyclic melanotropic peptide, is a central initiator of erection in men with psychogenic erectile dysfunction (ED). We assessed the erectogenic properties and side effect profile of MT II in men with organic ED.

Methods

* * Nine subjects aged 37 to 67 years (mean 57.4) with erectile dysfunction were enrolled in the study if history, physical examination, and nocturnal penile tumescence (NPT) were consistent with an organic etiology. Pre-trial NPT revealed a mean of 0.5 erectile events per night, lasting a mean of 6 minutes (range 0-18) with a mean maximum rigidity of 36%. A serum biochemical and hormonal profile was obtained prior to entry into the study and subjects were required to fill out the IIEF]
Results

* * Eight of 9 subjects reported Rigiscan and subjective evidence of erections with MT II while none did so on placebo. Two patients reported erections outside of the 6-hour observation period. Mean values for rigidity (visual analog scale) were 7.37 on MTII versus 0.0 for placebo. Subjectively reported duration of erection averaged 64.1 minutes on MT II. Mean level of sexual desire was 2.12 after MT II versus 1.06 on placebo. Nausea, stretching and yawning, and flushing occurred more frequently with MTII, but only 2 of 17 injections resulted in severe nausea.

Conclusion

* * The erectogenic properties of MT II are not limited cases of psychogenic ED; men with a variety of organic etiologies developed penile erections in response to our standard dose of 0.025 mg/kg. The unexpected finding of increased sexual desire warrants further investigation of central initiators on disorders of desire.