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Key findings

Study questions effectiveness of commonly used medication for back pain

April 6, 2016

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In a VA San Diego study, patients with back pain took gabapentin or identical-looking sugar pills for 12 weeks. (Photo by Mitch Mirkin. For illustrative purposes only.)

In a VA San Diego study, patients with back pain took gabapentin or identical-looking sugar pills for 12 weeks. (Photo by Mitch Mirkin. For illustrative purposes only.)

A study at the VA San Diego Healthcare System suggests the pain medication gabapentin is no more effective than placebo at treating chronic low back pain.

The findings appeared online March 8, 2016, in the journal Pain.

Chronic low back pain is a common disabling condition, and doctors have found few effective treatments.

Gabapentin, sold as Neurontin and a couple of other brands, is used mainly to treat seizures. It is also recommended by many clinical practice guidelines as a first-line treatment for neuropathic pain. Partly for that reason, it is often prescribed for low back pain. There's also some evidence of its efficacy for pain relief in fibromyalgia. However, few controlled trials have tested the drug for low back pain.

With VA funding, researchers with VA and the University of California, San Diego, conducted a trial to explore the question. They randomly assigned 108 patients with chronic back pain to either gabapentin or sugar-pill placebo. Both treatments were packaged in identical gelatin capsules.

"The researchers urge further studies to test whether the drug may in fact be of some use for chronic low back pain, especially when the cause is nerve-related."

Patients took gabapentin or sugar pills in the same amounts and frequency during the 12-week study. The two groups completed questionnaires about pain intensity, mood, and quality of life throughout the trial. Both patients and the study physician were blinded as to which group each participant was assigned.

Gabapentin no more effective than placebo

After 12 weeks, a majority of study participants reported at least a 30 to 50 percent decrease in pain intensity from the start of the study. However, the difference between pain reduction in the gabapentin and placebo groups was not significant. The study also did not detect differences between the groups for disability scores.

The researchers also tested whether the drug might be more effective at treating back pain that radiates into the legs, because such pain could be a sign of neuropathy, such as in sciatica. But participants with or without radiating pain had similar results.

The team also tested the concentrations of gabapentin in blood plasma for those in the drug group. Concentrations were generally in the range obtained in studies of painful neuropathy. The researchers found no difference in pain intensity based on blood levels of the drug.

Certain adverse side effects occurred more often in the group taking gabapentin. They included fatigue, dry mouth, difficulty concentrating, memory problems, problems with visual focus, and loss of balance. Overall, the medication was less tolerable than the investigators anticipated based on its reputation. On the other hand, the frequency of various other side effects was similar between the two groups.

The authors note several limitations to the study. They say it may have been difficult to detect any effect from gabapentin because of the relatively small number of participants, and because the study excluded those with more severe pain. Also, chronic back pain is not a single diagnosis, and the study's inclusion of patients with pain from various causes may have made it harder to tease out any possible benefits of the drug. Finally, the study did not examine indirect effects of the drug, such as sleep changes, nor how it works in combination with other treatments.

While the results may spur clinicians to take a closer look at their use of the drug for back pain, the researchers urge further studies to better clarify whether gabapentin may in fact be of some use for chronic low back pain, especially when the cause is nerve-related.


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