Efficacy of Gabapentin in Migraine Prophylaxis

Abstract

Objective.—To compare gabapentin with placebo for use as a prophylactic agent in patients with migraine (with or without aura). Study Design and Treatment.—After screening, a 4‐week, single‐blind, placebo baseline period was followed by a 12‐week, double‐blind, treatment period. The 12‐week treatment period consisted of a 4‐week titration phase and an 8‐week stable‐dosing phase. During the 4‐week titration phase, patients were started on one 300‐mg capsule of gabapentin or matching placebo. Patients were titrated weekly from 900 mg/day (end of week 1) to 2400 mg/day (end of week 4) and had to be receiving a stable dose of study medication by the end of the titration period. Study medication was to be given on a three‐times‐a‐day dosing regimen. Methods.—The study hypothesis was defined a priori as a lower 4‐week migraine rate during the second stabilization period for the gabapentin‐treated patients as compared with the placebo‐treated patients. The analyses were performed with the 4‐week migraine rate at baseline as a covariate and center as a blocking factor. Results.—At seven participating centers, 143 patients with migraine were randomized in a 2:1 ratio and received either gabapentin (n = 98) or matching placebo (n = 45). Thirty‐three patients (24.1%) discontinued prematurely from the study, including 24 (24.5%) of 98 gabapentin‐treated patients and 9 (20.0%) of 45 placebo‐treated patients; the majority of patients discontinued due to adverse events (16 [16.3%] of 98 gabapentin‐treated patients; 4 [8.9%] of 45 placebo‐treated patients). Patients included in the analysis were evenly balanced for age, sex, race, weight, and height. The majority of these patients were white (80 [92.0%] of 87) and women (72 [82.8%] of 87), with a mean age of approximately 39.4 years and a history of migraine episodes for a mean of about 21 years. At the end of the 12‐week treatment phase, the median 4‐week migraine rate was 2.7 for the gabapentin‐treated patients maintained on a stable dose of 2400 mg/day and 3.5 for the placebo‐treated patients ( P = .006), compared with 4.2 and 4.1, respectively, during the baseline period. Additionally, 26 (46.4%) of 56 patients receiving a stable dose of 2400 mg/day gabapentin and 5 (16.1%) of 31 patients receiving placebo showed at least a 50% reduction in the 4‐week migraine rate ( P = .008). The average number of days per 4 weeks with migraine was also statistically significant and favored gabapentin ( P = .006) during stabilization period 2. The median change in 4‐week headache rate was statistically significant as well ( P = .013). The most frequently reported adverse events for both treatment groups were asthenia, dizziness, somnolence, and infection. Adverse events determined by the investigator to be associated with study drug resulted in patient withdrawal in 13 (13.3%) of 98 gabapentin‐treated patients and 3 (6.7%) of 45 placebo‐treated patients. Somnolence and dizziness accounted for many of the premature withdrawals among those taking gabapentin. Conclusion.—Gabapentin is an effective prophylactic agent for patients with migraine. In addition, gabapentin appears generally well tolerated with mild to moderate somnolence and dizziness.