1. ¹Palatin Technologies, Inc., Cranbury, New Jersey, USA
2. ²Department of Psychiatry, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
3. ³Advanced Biomedical Research, Pennington, New Jersey, USA

Correspondence: LE Diamond, Palatin Technologies, Inc., 4C Cedar Brook Drive, Cranbury, NJ 08540, USA. E-mail: ldiamond@palatin.com

Received 29 April 2003; Revised 1 August 2003; Accepted 13 September 2003.

Abstract

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 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.