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

Abstract

Three hundred and four patients with non-psychogenic erectile dysfunction (ED) completed a dose assessment phase with intracavernosal injection utilizing 25 mg vasoactive intestinal polypeptide (VIP) combined with phentolamine mesylate 1.0 mg (VIPaP-1) or 2.0 mg (VIPaP-2) in an autoinjector 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-®ve patients were subsequently treated in a placebo controlled phase. 75.1% responded to VIPaP-1, 12% to placebo (P`0.001); 66.5% responded to VIPaP-2, 10.3% to placebo (P<0.001), with the median duration of erection of 54 min. The principal adverse event was transient facial¯ushing 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 satis®ed with the drug and auto-injector, respectively. Over 81% of patients and 76% of partners reported an improved quality of life.

Erectile dysfunction: from biochemical pharmacology to advances in medical therapy

“…Nowadays injection of phentolamine (0.25±1 mg) in combination with papaverine (7.5±30 mg), PGE 1 (5±40 mg) or papaverine and PGE 1 (triple drug) results in a greater than 70% success rate (59). Promising results are also obtained with intracavernosal injection of a combination of phentolamine and VIP (60,61). Conversely, intracavernous administration of phenoxybenzamine is not still in use due to local side effects as ®brosis and prolonged erection.…”

Mechanisms of Penile Erection and Basis for Pharmacological Treatment of Erectile Dysfunction

“…VIP given intravenously can produce hypotension, tachycardia, and flushing (Frase et al, 1987;Krejs, 1988). However, the plasma half-life of the peptide is short, which may contribute to the fact that systemic side effects are rare when it is administered intracavernosally (McMahon, 1996;Dinsmore et al, 1999;Sandhu et al, 1999).…”

Current perspectives on intracavernosal pharmacotherapy for erectile dysfunction

“…Final results of the UK multicenter placebo-controlled Invicorp 1 -trial were published by Sandhu in 1999 and are summarized in Table 9. 52 In this prospective trial, the total drop-out rate (calculated from the date of ®rst-patient-in and last-patient-out after 6 months was 65.5% (199a304) and was thus considerably higher than in all other alprostadil injection trials. 43,46,52 There were no comments about the reasons for this high drop-out rate.…”