Naltrexone-induced augmentation of sexual response in men

Background. To ascertain the role of endogenous opioids in sexual response, naltrexone, an opiate receptor antagonist, was administered to men, and it s effect on selected self-report measures of sexual response to masturbatio n was recorded. Methods. The data are based on results from 20 healthy, sexually active (al one or with a partner) men, aged 20-29 years, who ingested naltrexone (25 m g/day X 3) or placebo in a randomized, double-blind crossover design. There was at least a lit-day interval between drug and placebo treatment. Betwee n 18 and 22 h after the most recent dose of drug or placebo, subjects viewe d sexually explicit videos in privacy for 2 h. They were instructed to mast urbate and have as many orgasms as desired. The following three different s elf report measures of their responses were recorded: number of orgasms; in tensity of sexual arousal, and orgasmic intensity. Results. Under the naltrexone condition, the volunteers experienced a signi ficantly greater mean number of orgasms (3.4 +/- 0.2 SEM) than under the pl acebo condition (2.6 +/- 0.3). The total number of orgasms was 67 under the naltrexone condition and 51 under the placebo condition. At the first orga sm, the measure of intensity of arousal was significantly greater in the na ltrexone (3.9 +/- 0.2) than placebo (3.4 +/- 0.2) condition, and the measur e of orgasmic intensity was significantly greater in the naltrexone (3.7 +/ - 0.2) than in the placebo (3.0 +/- 0.3) condition. Conclusions. The present study provides evidence that endogenous opioids mo dulate orgasmic response and the perceived intensity of sexual arousal and orgasm in men. The findings suggest that naltrexone could be clinically use ful in cases of inhibited sexual desire and erectile dysfunction. (C) 2001 IMSS. Published by Elsevier Science Inc.