Anti-seizure drugs, which are often prescribed by doctors and pain specialists to treat back and neck pain is ineffective and unsafe, with a higher risk of adverse effects, according to a systematic review of nine placebo-controlled randomized trials published online in the Canadian Medical Association Journal on July 3.
Millions of people experience low back pain, which causes more disability than any other health condition. Generally, clinical guidelines for low back pain recommend nonpharmacologic interventions and nonopioid analgesics, rather than anti-seizure medication. Yet, previous findings show a substantial increase in the use of anti-seizure medications such as pregabalin (Lyrica) and gabapentin (Neurontin) for treating back and neck pain. Classified as gabapentinoids, these drugs blunt pain signals in the nerves and are typically recommended for neuropathic pain.
The efficacy and safety of these drugs for chronic low back and lumbar radicular pain such as sciatica—pain that originates from the lumbar region or hips—remain unclear. Studies have been limited to populations with chronic back pain and conclusions have been conflicting and limited.
Prompted by this lack of data, a team of researchers from the University of Sydney used five databases to identify studies that compared an anti-seizure drug to placebo in patients with nonspecific low back pain, sciatica, or inflammation of the nerves.
They selected a total of nine trials that compared topiramate (Topamax), gabapentin, or pregabalin to placebo in 859 participants. The average age of participants in the treatment group was 50.8. In the placebo group it was 51.5.
To determine pain and disability, researchers reviewed data at different times during the studies: two weeks after participants were randomized to the different groups; between two weeks and three months; between three months and 12, and longer than 12 months.
To measure safety outcomes, the researchers counted the number of participants with any serious side effects throughout the study.
Trials that investigated low back pain with or without radiating leg pain showed that gabapentinoids did not reduce pain or disability compared with placebo in the short or intermediate term. For spinal nerve pain, gabapentinoids had no effect on pain or disability. The use of these drugs was also associated with an increased risk of adverse events compared with placebo.
In one study, the researchers identified a total of 19 side effects such as drowsiness, dizziness, and nausea in 31 participants who received gabapentin for chronic low back pain compared to 13 side effects in 34 participants in the placebo group.
Meanwhile, the use of topiramate led to a "small clinically worthwhile" effect for pain in the short term, but no effect on disability, the researchers reported.
In two studies that investigated topiramate, one did not find an increased risk of side effects, but an active placebo (diphenhydramine) used in the study had a similar sedative side effect profile to topiramate. The second study reported 21 side effects in topiramate and 10 in the placebo group. However, this study did not report the total number of participants who experienced side effects.
The researchers’ review found strong evidence that gabapentinoids are not effective for treating low back pain and have too high a risk of side effects.
Currently, a clinical practice guideline from the American College of Physicians does not mention anticonvulsants as a treatment option for low back pain, since there’s insufficient evidence to support its efficacy and safety.