Drugs in early clinical development for the treatment of female sexual dysfunction.
INTRODUCTION Low sexual desire in women may result from a relative insensitivity of the brain for sexual cues. Administration of sublingual 0.5 mg testosterone (T) increases the sensitivity of the brain to sexual cues. Sexual stimulation in the brain is necessary for phosphodiesterase type 5 inhibitor (PDE5i)-mediated increase in genital sexual response. Accordingly, a single dose of T+PDE5i might enhance sexual responsiveness, especially in women with low sensitivity for sexual cues. AIM To assess the hypothesis that treatment with on-demand use of T+PDE5i improves sexual functioning, particularly in women who suffer from Hypoactive Sexual Desire Disorder (HSDD) as the result of a relative insensitivity for sexual cues. METHODS In a randomized, double-blind, placebo-controlled, crossover design, 56 women with HSDD underwent three medication treatment regimes (placebo, T+PDE5i, and T with a serotonin receptor agonist; see also parts 1 and 3), which lasted 4 weeks each. In a participant-controlled ambulatory psychophysiological experiment at home (the first week of each drug treatment), physiological and subjective indices of sexual functioning were measured. In a bedroom experiment (the subsequent 3 weeks), sexual functioning was evaluated following each sexual event after the self-administration of study medication. Subjective evaluation of sexual functioning was also measured by weekly and monthly reports. MAIN OUTCOME MEASURES Subjective: sexual satisfaction, experienced genital arousal, sexual desire. Physiological: vaginal pulse amplitude. Cognitive: preconscious attentional bias. RESULTS T+PDE5i, as compared with placebo, significantly improved physiological and subjective measures of sexual functioning during ambulatory psychophysiological lab conditions at home and during the sexual events, in women with low sensitivity for sexual cues. CONCLUSIONS The present study demonstrated that on-demand T+PDE5i is a potentially promising treatment for women with HSDD, particularly in women with low sensitivity for sexual cues.