Fibromyalgia (FM) is a disorder which is felt to be due to abnormal processing of neurotransmitters in the brain. Gabapentin (Neurontin) is a drug that has been shown to block pain signal processing and has demonstrated efficacy for diabetic and other types of neuropathy. Rheumatologists have used gabapentin to treat FM for years “off-label” since it has no FDA approval yet for use in FM.
A new study shows that it also significantly reduces neuropathic pain in fibromyalgia. This may provide the impetus for the FDA to approve gabapentin.
In a multicenter trial, researchers randomized 150 patients with fibromyalgia-related pain to gabapentin 1,200-2,400 mg a day or placebo for 12 weeks.
The Brief Pain Inventory (BPI), a pain severity score ranging from 0 (no pain) to 10 (worst imaginable pain), was used to determine the primary outcome. Response was defined as a reduction of 3 or more points.
Patients on gabapentin had a significantly greater improvement in the BPI average pain severity score at week 12. The average reduction in BPI was 0.92 greater in the gabapentin group compared with the placebo group. Response was achieved by 51% of patients on gabapentin compared with 31% of placebo-treated patients.
Gabapentin resulted in significant improvement in the average BPI pain interference score, patient assessment of fibromyalgia impact on health, overall impression of severity and sleep disturbance. However, the investigators observed no changes on the mean tender point pain score. (Tender points are often used by physicians to assess the degree of pain a patient has as a result of their fibromyalgia).
Gabapentin effectively reduced pain in patients with fibromyalgia and it also improved sleep, which is commonly reported to be disrupted in patients with fibromyalgia.
Researchers also pointed out that gabapentin was well tolerated at doses between 1200 and 2400 mg/day. More patients on active treatment reported feeling sleepy, dizziness and weight gain, although weigh gain was not seen on clinical examination.
The researchers concluded that gabapentin is an option for patients looking for reduction in pain and improved sleep.
(Arnold LA, Goldenberg DL, Stanford SB, Lalonde JK, Sandhu HS, Keck PE, Welge JA, Bishop F, Stanford KE, Hess EV, Hudson JI. Gabapentin in the treatment of fibromyalgia: a randomized, double-blind, placebo-controlled, multicenter trial.Arthritis Rheum 2007;56:1336-1344).