TREATMENT OF IDIOPATHIC ERECTILE DYSFUNCTION IN MEN WITH THE OPIATE ANTAGONIST NALTREXONE - A DOUBLE-BLIND-STUDY

Opiate antagonists can indirectly stimulate the secretion of luteinizi ng hormone (LH) and testosterone, as well as sexual functions in anima ls and humans. We therefore treated 20 otherwise healthy men with idio pathic erectile dysfunction aged 46.3+/-2.7 years (mean +/- SE, range 23.9-63.3) in a double-blind study with an opiate antagonist, naltrexo ne, or placebo. The erectile dysfunction of these men had persisted fo r 3.6+/-0.5 years despite libido maintenance; standard procedures had excluded any organic causes. Trial duration was 12 weeks overall. Afte r a 4-week forerun, the patients received at first 25 mg naltrexone/da y orally or placebo for 4 weeks followed by 4 weeks of a 50-mg dose of naltrexone/day or placebo. Each day the patients filled out a questio nnaire detailing libido, degree of erection, frequency of sexual inter course, and spontaneous morning erections. Serum concentrations of gon adotropins and testosterone were determined radioimmunologically in th e initial stage and at the end of each phase. Both patient collectives had similar initial factors. The group treated with naltrexone showed a significant rise in spontaneous early morning erections during the treatment: from 2.8+/-0.3 to 4.2+/-0.3 a week (P<0.001). The placebo g roup showed no significant change in spontaneous erections (2.4+/-0.3 and 2.6+/-0.3, respectively). The subjective parameters, however, such as libido, degree of erection, and frequency of sexual intercourse sh owed no significant difference within each group. There was no differe nce in LH, follicle-stimulating hormone, or testosterone concentration s in both groups. Thus, treatment with naltrexone significantly raises the rate of spontaneous early morning erections when compared to cont rols. Other parameters, especially those of the frequency of sexual in tercourse, were not significantly influenced by the dosage of the admi nistered opiate antagonist The significance of the naltrexone-induced rise in spontaneous morning erections requires more evaluation in a gr eater collective of patients with idiopathic erectile dysfunction.