A double blind, placebo controlled study of intracavernosal vasoactive intestinal polypeptide and phenotolamine mesylate in a novel auto-injector for the treatment of non-psychogenic erectile dysfunction

Int J Impot Res. 1999 Apr;11(2):91-7. doi: 10.1038/sj.ijir.3900388.


Three hundred and four patients with non-psychogenic erectile dysfunction (ED) completed a dose assessment phase with intracavernosal injection utilizing 25 micrograms vasoactive intestinal polypeptide (VIP) combined with phentolamine mesylate 1.0 mg (VIP/P-1) or 2.0 mg (VIP/P-2) in an auto-injector for a response rate of 83.9%. In a sub-group of 183 patients who withdrew from one or more previous ED therapies, 82% responded with an erection suitable for intercourse. One hundred and ninety-five patients were subsequently treated in a placebo controlled phase. 75.1% responded to VIP/P-1, 12% to placebo (P < 0.001); 66.5% responded to VIP/P-2, 10.3% to placebo (P < 0.001), with the median duration of erection of 54 min. The principal adverse event was transient facial flushing in 2770 injections (33.9%). There was no pain post injection and two episodes of priapism (0.05%). Only nine patients withdrew because of adverse events. Over 85% and 95% of patients were satisfied with the drug and auto-injector, respectively. Over 81% of patients and 76% of partners reported an improved quality of life.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Cross-Over Studies
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Erectile Dysfunction / drug therapy*
  • Humans
  • Injections / methods
  • Male
  • Middle Aged
  • Phentolamine / administration & dosage*
  • Phentolamine / adverse effects
  • Phentolamine / therapeutic use
  • Placebos
  • Vasoactive Intestinal Peptide / administration & dosage*
  • Vasoactive Intestinal Peptide / adverse effects
  • Vasoactive Intestinal Peptide / therapeutic use
  • Vasodilator Agents / administration & dosage
  • Vasodilator Agents / therapeutic use


  • Placebos
  • Vasodilator Agents
  • Vasoactive Intestinal Peptide
  • Phentolamine