Pilot study of the transdermal application of testosterone gel to the penile skin for the treatment of hypogonadotropic men with erectile dysfunction

Androgens influence important central and peripheral mechanisms of the erec tile system. The relevance of a moderate decrease of serum testosterone lev el for erectile dysfunction (ED) has not been clarified so far. The aim of our study was to offer an easy transcutaneous method of androgen applicatio n. A previous study on the pharmacokinetic profile of the testosterone gel applied, showed marked elevation of the serum levels of testosterone. In ou r study, 46 hypogonadal patients with ED and total lack of vaginal penetrat ion applied testosterone gel (4 mg/day; supplied by Azupharma, Germany) to the penile skin twice a day over 6-8 weeks, after a run-in period with plac ebo gel of 2 weeks. All patients showed decreased testosterone serum levels (<3 ng/ml) in at least two morning samples over a period of 3 weeks before treatment. Psychogenic etiology was excluded by a sexual psychologist. Pat ient age was 37-69 years (mean 53.5). Three patients (6.5%) responded to pl acebo in the run-in phase and were withdrawn from further treatment. Fiftee n patients (32.6%) showed improved erection, allowing penetration and sexua l intercourse. Twenty-eight patients (60.9%) did not respond to therapy. Lo cal genital skin irritation was not observed. Elevation of peripheral testo sterone was not correlated to a positive therapy response. A success-rate o f 32.6% in this group of patients after exclusion of psychogenic patients a nd placebo-responders seems to justify further investigations. A medication period of 6-8 weeks is most probably too short to induce imaginable regene rative effects of testosterone on the erectile system. We therefore suggest that future double-blind and placebo-controlled studies should be designed for a minimum of 3 months. Testosterone gel may be a cost effective form o f androgen administration.