The function of sildenafil on female sexual pathways: a double-blind, cross-over, placebo-controlled study

To determine the changes, if any, on female sexual pathways using sildenafil (primary outcome), and to verify the safety of this drug (second outcome).

Following previous research on symptomatic women, we wanted to study the effects of sildenafil on asymptomatic women. We would like to make it clear from the outset that this study is part of an ongoing line of research and this drug, and others of its type, should be used under strict medical supervision only on symptomatic patients. A randomized double-blind cross-over, placebo-controlled study was conducted at the Family Planning Centre of the Group for Sexological Research, Department of Microbiological and Gynecological Science, School of Medicine, University of Catania, Italy. Sixty-eight healthy volunteer women aged 19-38 years, asymptomatic for sexual disorders, were enrolled. The study consisted of 4 weeks sildenafil, 2 weeks washout, and 4 weeks placebo, by two possible sequences: sildenafil 50 mg, washout, placebo; or placebo, washout, sildenafil 50 mg. Efficacy of sildenafil was assessed by the Personal Experiences Questionnaire (PEQ) based on the 5-point Likert scale. The questionnaire quantified subjective sexual aspects at baseline, during washout, after treatments, and at the follow-ups. Statistical analysis was done with the Wilcoxon's rank-sum test and Student's t-test.

50/68 women completed the study at the first follow-up, and 38 women reached the second follow-up. Six women withdrew because of adverse events. Sildenafil improved arousal (P<0.001), orgasm (P<0.05), and enjoyment (P<0.001) with respect to placebo. Significant differences were noted during sildenafil usage with respect to the baseline for arousal (P<0.01), orgasm (P<0.001), and sexual enjoyment (P<0.001). The adverse events were transient and mild or moderate.

Our study suggests that sildenafil acts on the different sexual pathways in healthy women, improving their sexual experience. This study could help to understand the physiologic and pathophysiologic aspects of female sexuality. In comparison with current psychosexual therapies, which are long-term, compliance would be improved with use of this drug. Additional studies are required to define the use of sildenafil in a clinical setting.