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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


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™ in healthy subjects without visual sexual stimulation (VSS) and in Viagra®-responsive ED patients with VSS. In healthy subjects, mean Cmax and AUC(0–t) increased in a dose-dependent manner. Median Tmax was 0.50 h and mean t1/2 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.

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We thank Annette Shadiack, Wilfredo Garcia, and Ramzey Odetalla for their valuable contributions to these studies

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Correspondence to L E Diamond.

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Diamond, L., Earle, D., Rosen, R. et al. 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 16, 51–59 (2004).

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  • erectile dysfunction
  • melanocortin
  • PT-141

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