Opiate antagonists in erectile dysfunction: a possible new treatment option? Results of a pilot study with naltrexone.

Opioids have an inhibitory effect on sexual functions in both animals and humans. Twenty patients with idiopathic, nonvascular, nonneurogenic erectile dysfunction were treated with the opiate receptor antagonist naltrexone in a randomized, placebo-controlled, double-blind study for 8 weeks. Libido and frequency of sexual intercourse were not significantly altered, but early-morning erections increased significantly under naltrexone therapy. This response was not related to levels of androgens or gonadotropins, neither was it dose dependent. There was no change in any of the measured parameters under placebo. Further clinical studies with the substance should be conducted to evaluate its possible role in the oral treatment of male impotence.