Randomized placebo controlled trial of lofexidine hydrochloride for chronic pelvic pain in women

Abstract

We hypothesised that the orally-active alpha(2)-adrenoceptor agonist lofexidine hydrochloride would ameliorate chronic pelvic pain in women. A randomized placebo-controlled parallel group trial was undertaken in the University Hospital Gynaecology Clinic. Women with pelvic pain of at least 6 months duration were eligible, and were randomized using a sealed envelope system to receive up to 600 mg lofexidine hydrochloride twice daily over 8 weeks or placebo. Outcome measures were summary and daily diary visual analog scales for pain (VAS) and a 5 point self rating scale. 9/19 women randomized to lofexidine completed the study compared to 14/20 of those randomized to placebo. Intention-to-treat analysis showed that 4/19 in the lofexidine group achieved 50% or greater reduction in VAS compared with 8/20 in the placebo group (OR 2.5, 95% CI 0.6--10.3). Summary and diary VAS were closely correlated. Within the limits of a small study with power to detect only a substantial effect, we conclude that lofexidine hydrochloride is not effective for the treatment of chronic pelvic pain.