Gabapentin and pregabalin (Lyrica) are prescribed frequently for lumbosacral radicular pain, despite a lack of evidence that they are effective for this condition. In this randomized trial from Australia, researchers randomized 209 patients with sciatica to receive either pregabalin (titrated from 150 mg to 600 mg, depending on response and side effects) or placebo for as long as 8 weeks. At enrollment, duration of pain had been 1 week to 1 year (mean, 2 months); all patients had pain radiating below the knee and either dermatomal pain distribution, motor or sensory deficit, or diminished reflex. The primary outcome was leg pain at 8 weeks.
Improvement in the mean leg-pain score at 8 weeks actually was slightly greater in the placebo group than in the pregabalin group (decrease of 3.0 vs. 2.6 points, from a mean baseline of ≈6.1 on a 10-point scale), but the difference was not statistically significant; pain scores remained similar in the two groups at 1 year. Moreover, the groups did not differ on any secondary outcome (e.g., ratings of disability, quality of life, and global perceived effect). However, the frequency of side effects was significantly higher with pregabalin than with placebo — dizziness was most common (40% vs. 13%).
Pregabalin does not relieve pain associated with sciatica and should not be prescribed for this purpose; presumably, the same holds true for the related drug gabapentin. This finding is not surprising: Although pregabalin has some efficacy — and is FDA-approved for use — in patients with postherpetic neuralgia or diabetic peripheral neuropathy, the pathogenesis of pain in those conditions is different from that of radicular pain.