Dose-response studies of intracavernous injection therapy with alprostadil in Asian and Australian men with erectile dysfunction

Abstract

This is the first report on dose-response results with alprostadil (Caverject ® Sterile Powder), a formulation of prostaglandin E 1 (PGE 1), for the treatment of erectile dysfunction (ED) in 365 Asian and Australian men, 21 to 75 years of age (mean, 48.9 years) with ED from 2 months' to 35 years' duration (mean, 3.8 years). Seven Asian centers conducted an open-label, dose-escalation study starting with 2.5- or 5μg doses titrated up to a maximum of 40 or 60 μg. Two Australian centers used a double-masked, placebo-controlled, crossover protocol that randomized patients to 2.5-, 5-, 10-, or 20μg dose levels of alprostadil in three formulations (Caverject Aqueous Injection, Caverject Sterile Powder, or Prostin VR ®), with dose determined by the dose they had used at home. For all centers combined, 74.0% of patients (270/365) had optimal erectile responses (defined as full erection sufficient to achieve vaginal penetration and lasting from 30 to 60 minutes). The Asian optimal response was 83.0% (244/294). Optimal erectile response was achieved in 66.7% of Australian men (10/15) using 20 μg of alprostadil sterile powder. Low doses (2.5 and 5 μg) produced optimal erectile response in 25.4% of all patients. No clear correlations were found between erectile response and country of origin, age, or duration of ED. In patients with psychogenic ED, 95% achieved optimal erectile response (mean dose, 11.5 μg) and 100% of patients with ED of neurogenic origin had an optimal erectile response (mean dose, 15.3 μg). Thirty-nine (10.7%) of 365 patients reported 53 episodes of penile pain or pain at the injection site; 1 patient discontinued the study. No significant differences were found when comparing erectile response between Australian and Asian men and those reported for men in European and North American countries. Low starting doses (2.5 to 5 μg) should be used and titrated slowly upward to determine each patient's optimal effective response, regardless of the patient's ethnic origin or age or the duration of ED.