Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild-to-moderate erectile dysfunction

Int J Impot Res. 2004 Feb;16(1):51-9. doi: 10.1038/sj.ijir.3901139.


PT-141, a cyclic heptapeptide melanocortin analog, was evaluated following intranasal administration in healthy male subjects and in Viagra-responsive erectile dysfunction (ED) patients. Erectile response was assessed by RigiScan trade mark in healthy subjects without visual sexual stimulation (VSS) and in Viagra-responsive ED patients with VSS. In healthy subjects, mean C(max) and AUC((0-t)) increased in a dose-dependent manner. Median T(max) was 0.50 h and mean t(1/2) ranged from 1.85 to 2.09 h. In both studies, an erectile response induced by PT-141 administration was statistically significant, compared to placebo, at doses greater than 7 mg, with the onset of the first erection occurring in approximately 30 min. PT-141 was safely administered and well tolerated in both studies. A maximum-tolerated dose was not identified. Flushing and nausea were the most common adverse events reported in both studies and no clinically significant changes in vital signs, laboratory tests, ECGs, or physical exams were observed. Based upon its erectogenic potential and tolerability profile, PT-141 is a promising candidate for further evaluation as a treatment for male ED.

Publication types

  • Clinical Trial
  • Clinical Trial, Phase I
  • Randomized Controlled Trial

MeSH terms

  • Administration, Intranasal
  • Adolescent
  • Adult
  • Double-Blind Method
  • Erectile Dysfunction / drug therapy*
  • Humans
  • Male
  • Middle Aged
  • Penile Erection / drug effects
  • Peptides, Cyclic / administration & dosage*
  • Peptides, Cyclic / adverse effects
  • Peptides, Cyclic / pharmacokinetics*
  • Placebos
  • Receptors, Melanocortin / agonists*
  • Severity of Illness Index
  • Treatment Outcome
  • alpha-MSH


  • Peptides, Cyclic
  • Placebos
  • Receptors, Melanocortin
  • alpha-MSH
  • bremelanotide