Gabapentin for Pain: Balancing Benefit and Harm
Am Fam Physician. 2006 Feb 1;73(3):435.
Is gabapentin (Neurontin) effective for the treatment of acute and chronic pain?
At high dosages, gabapentin is moderately effective for neuropathic pain, although adverse effects are experienced as often as benefit.
Gabapentin is widely used for the treatment of pain, particularly in patients with chronic neuropathic pain. Wiffen and colleagues performed a systematic review of randomized trials assessing the use of gabapentin in acute, chronic, or cancer pain, and found 15 studies with a total of 1,468 patients. Only one study involved patients with acute pain. The remainder enrolled patients with postherpetic neuralgia (two studies), diabetic neuropathy (seven studies), or cancer-related pain, phantom limb pain, Guillain-Barré syndrome, spinal cord injury, and various neuropathic pains (one study each).
Gabapentin was found ineffective for acute pain. The studies of neuropathic pain used a wide variety of dosages, typically 900 to 2,400 mg per day, and in one case up to 3,600 mg per day (the maximum recommended dosage according to the package labeling is 1,800 mg per day).
Data could be combined for six studies of neuropathic pain. In these trials, 42 percent of patients improved with gabapentin versus 19 percent with placebo, giving a combined number needed to treat (NNT) of 4 (i.e., four patients must be treated for one patient to experience an improvement in pain). However, adverse effects were common at the high dosages used in these studies, with 24 percent of patients experiencing dizziness, 20 percent somnolence, 10 percent headache, 10 percent diarrhea, and 7 percent confusion. The overall number needed to harm for adverse effects was also 4. Thus, for every patient who experiences a reduction in pain, another experiences an adverse effect.
The modest benefit of gabapentin for neuropathic pain must be balanced against its adverse effects. Whether this trade-off is worthwhile should be decided by the individual patient. The authors of this review report that based on preliminary data tricyclic antidepressants (NNT = 2) and carbamazepine (Tegretol; NNT = 1.7) are at least as effective as gabapentin and are less expensive (although generic gabapentin costs about one half as much as Neurontin). It is important that physicians carefully assess the balance between benefit and harm for their patients after a therapeutic trial rather than continuing a course of medication indefinitely.
Wiffen PJ, et al. Gabapentin for acute and chronic pain. Cochrane Database Syst Rev. 2005;(3):CD005452.
Copyright © 2006 by the American Academy of Family Physicians.
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