Gabapentin ineffective for vulvodynia

Reference

Brown CS, Bachmann GA, Wan J, Foster DC; Gabapentin (GABA) Study Group. Gabapentin for the treatment of vulvodynia: A randomized controlled trial. Obstet Gynecol 2018;131(6):1000-1007.

Synopsis

This trial was a double-blind placebo-controlled crossover trial of extended-release gabapentin for the treatment of penetrative vulvodynia among women older than 18 years. The women were eligible if insertion of a tampon produced pain in the vulvar area of at least 4 on a scale of 0 to 10. They were randomized to receive initial treatment with gabapentin (n = 45) or identical-appearing placebo pills (n = 44). Established regimens of oral contraceptives, hormone therapy, and serotonin reuptake inhibitors were allowed to continue during the study. Rescue analgesics such as acetaminophen and nonsteroidal anti-inflammatories were allowed and documented, but topical medications or opioid analgesics were not allowed. The study duration was 16 weeks with dose titration, maintenance, and tapering in each half of the study period. The dose of active medication was titrated upward to 3000 mg, if tolerated. The actual dosage was 1200 mg to 3000 mg daily. Effect was measured by the pain response to the insertion of a tampon during the latter of 2 weeks of each maintenance phase. Analysis was by intention to treat, with the last observation carried forward in the case of drop-outs (n = 23). The sample size was calculated to assess a 1-point mean difference in pain score between groups. There were no statistically significant differences in mean pain scores between groups (3.9, 95% CI 3.4 - 4.5 vs 4.3, 3.7 - 4.9; P = .07). There were also no significant differences in the secondary outcomes of pain with sexual intercourse and daily (nonpenetration) vulvar pain.