Gabapentin Fails to Lessen Chronic Pelvic Pain Save

Lancet reports that in a randomized, blinded, controlled trial, gabapentin failed to significantly lower pain scores in women with chronic pelvic pain, and was associated with higher adverse event rates compared to placebo.

Gabapentin is FDA approved for use in postherpetic neuralgia in adults and as adjunctive therapy in the treatment of partial onset seizures.  Yet, gabapentin is widely prescribed for many off-label indications, including chronic pain and neuropathy, without substantial proven efficacy.  In addition to the overuse, there have been allegations of misuse and concerns about it's safety. 

Chronic pelvic pain affects 2–24% of women worldwide and the treatment options are limited. This UK multicenter study enrolled women with chronic pelvic pain and were randomized to receive gabapentin (up to 2700 mg daily) or matching placebo for 16 weeks. The dual primary outcome measures were worst and average pain scores assessed separately by numeric rating.

A total of 306 women were treated and after 16 weeks, there were no significant between-group differences in both worst and average numerical rating scale (NRS) pain scores. The mean worst NRS pain scores and change from baseline:

• Worst NRS Gabapentin: 7·1 (SD 2·6),  Mean change from baseline was −1·4 (SD 2·3)
• Worst NRS Placebo: 7·4 (SD 2·2), Mean change from baseline −1·2 (SD 2·1); p=0·47)

The mean average NRS pain score and change from baseline was

• Mean NRS Gabapentin: 4·3 (SD 2·3), Mean change from baseline was −1·1 (SD 2·0)
• Mean NRS Placebo: 4·5 (SD 2·2),  Mean change from baseline was −0·9 (SD 1·8); p=0·45)

Serious adverse events were greater in the gabapentin group (7% vs. 2%); and dizziness, drowsiness, and visual disturbances were more common in the gabapentin group.

Gabapentin failed to significantly lower pain scores in women with chronic pelvic pain. Given the degree of overuse and misuse of gabapentin, clinicians should consider alternatives to off-label gabapentin.