Kingswood, Australia—It’s not news to pharmacists, but medications such as gabapentin and pregabalin are increasingly prescribed to treat low back pain. A new study suggests that limited supporting evidence exists for the treatment and that it can be both ineffective and potentially harmful.

The report in CMAJ (Canadian Medical Association Journal) sought to gauge the efficacy and tolerability of the antiseizure drugs in the treatment of low back pain and lumbar radicular pain versus placebo.

“Clinically, the prescription of anticonvulsants for back and neck pain, including radicular pain in primary care, has increased by 535% in the last 10 years,” writes the Australian study team, led by University of Sydney, Sydney Medical School Nepean researchers.

In addition to seizures, the drugs are approved to treat a variety of conditions, including postherpetic neuralgia, fibromyalgia, and neuropathic pain associated with diabetes. Earlier this year, FDA administrator Scott Gottlieb said the FDA is looking at whether gabapentinoids are an addiction threat.

For the meta-analysis, a search was conducted in five databases for studies comparing an anticonvulsant to placebo in patients with nonspecific low back pain, sciatica, or neurogenic claudication of any duration. The outcomes were defined as:
• Self-reported pain, 
• Disability and 
• Adverse events 

The study team included nine trials comparing topiramate, gabapentin, or pregabalin to placebo in 859 participants. Nearly all, 14 of 15, comparisons found anticonvulsants were not effective in reducing pain or disability in low back pain or lumbar radicular pain, according to the researchers, who said  “there was high-quality evidence of no effect of gabapentinoids versus placebo on chronic low back pain in the short term (pooled mean difference [MD] -0.0, 95% confidence interval [CI] -0.8 to 0.7) or for lumbar radicular pain in the immediate term (pooled MD -0.1, 95% CI -0.7 to 0.5). The lack of efficacy is accompanied by increased risk of adverse events from use of gabapentinoids, for which the level of evidence is high.”

The study reports “moderate-to high-quality evidence that anticonvulsants are ineffective for treatment of low back pain or lumbar radicular pain” and “high-quality evidence that gabapentinoids have a higher risk for adverse events.”

“We have shown, with mostly high- and moderate-quality evidence, that common anticonvulsants are ineffective for chronic low back pain and lumbar radicular pain, and are accompanied by increased risk of adverse events,” write the study authors, who point out that their findings support recent guidelines from the U.S. and the United Kingdom that recommend against the use of anticonvulsants for treatment of back and neck pain.
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