Sildenafil citrate in the treatment of pain in primary dysmenorrhea: RCT

Human Reproduction, 08/16/2013  Clinical Article

Dmitrovic R et al. – A number of medications have been investigated to improve the treatment options for PD, but most have proven unsuccessful or to have an unfavorable risk/benefit ratio. Since PD is a condition that most women suffer from and seek treatment for at some point in their lives, this study offers hope that vaginal sildenafil citrate is a safe and effective option for patients who do not desire or are unresponsive to treatments now available on the market.
Methods

• A double–blind, randomized, controlled trial comparing vaginal preparation of sildenafil citrate (100 mg single dose) to a placebo in 62 PD patients at the time of painful menstruation was conducted.
• The primary outcome was total pain relief over 4 consecutive hours (TOPAR4) comparing sildenafil citrate to placebo, where higher TOPAR4 scores represent better pain relief.
• Secondary outcomes were pain relief as measured by the visual analog scale (VAS) and uterine artery pulsatility index (PI).
• Subjects were recruited from December 2007 to January 2011.
• The trial was stopped due to closeout of the funding for the study.
• Participants were women in good health, were aged 18–35 years and suffered from moderate to severe PD.
• They were randomized to either vaginal placebo or 100 mg vaginal sildenafil citrate in a 1:1 ratio using random permuted blocks having a block size of 4.
• At baseline and 1, 2, 3, and 4 h post–treatment, patients were asked to provide assessment of their degree of pain using two scales: (i) pain on the 5–level ordinal scale used for TOPAR4 calculation and (ii) pain level on the VAS.
• The study ended 4 h after treatment initiation.

Results

• Twenty–five subjects completed the study.
• Using the TOPAR4 score, the sildenafil citrate group had significantly better pain relief compared with the placebo group [mean (SD): 11.9 (3.2) versus 6.4 (2.1), respectively; difference in means = 5.3; 95% CI: (2.9,7.6); P < 0.001)].
• On the VAS, sildenafil citrate provided better pain relief than placebo at each time point.
• At the 2–h time point, the PI was significantly lower in the sildenafil citrate group compared with the placebo group [mean (SD): 1.6 (0.6) versus 2.3 (0.5), respectively; difference in means = –0.7; 95% CI: (–1.2, –0.1); P = 0.01)].