title: Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction.
abstract: OBJECTIVE
  To assess the safety, erectogenic properties, and effect on sexual desire of Melanotan II, a synthetic melanotropic initiator of erection, in men with erectile dysfunction and organic risk factors.
  
  
  METHODS
  Ten subjects were enrolled in a double-blind, placebo-controlled, crossover study. Melanotan II (0.025 mg/kg) and vehicle were each administered twice by subcutaneous injection; real-time RigiScan monitoring and a visual analog were used to quantify the erections during a 6-hour period. The level of sexual desire and side effects were recorded with a questionnaire.
  
  
  RESULTS
  Melanotan II initiated subjectively reported erections in 12 of 19 injections versus only 1 of 21 doses of placebo. The mean rigidity score of the responders was 6.9 on a scale of 0 to 10. The mean duration of tip rigidity greater than 80% was 45.3 minutes with Melanotan II versus 1.9 for placebo (P = 0.047). The level of sexual desire after injection was significantly higher after Melanotan II administration than after placebo. Nausea and stretching/yawning occurred more frequently with Melanotan II, and 4 of 19 injections were associated with severe nausea.
  
  
  CONCLUSIONS
  The erectogenic properties of Melanotan II are not limited to cases of psychogenic erectile dysfunction; men with a variety of organic risk factors developed penile erections. The finding of increased sexual desire warrants further investigation of centrally acting agents on disorders of sexual desire.
authors.affiliation: Section ofUrology, University of Arizona College of Medicine, Tucson, Arizona, USA.
authors.forename: H
authors.initials: H
authors.lastname: Wessells
authors.forename: D
authors.initials: D
authors.lastname: Gralnek
authors.forename: R
authors.initials: R
authors.lastname: Dorr
authors.forename: V J
authors.initials: VJ
authors.lastname: Hruby
authors.forename: M E
authors.initials: ME
authors.lastname: Hadley
authors.forename: N
authors.initials: N
authors.lastname: Levine
mesh_terms: D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D004311:Double-Blind Method; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009325:Nausea / Q000139:chemically induced; D010147:Pain Measurement; D010410:Penile Erection / Q000187:drug effects*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D012307:Risk Factors; D000521:alpha-MSH / Q000031:analogs & derivatives* / Q000494:pharmacology*
chemical_list: D010456:Peptides, Cyclic; C079282:melanotan-II; D000521:alpha-MSH