Lack of efficacy of the selective iNOS inhibitor GW274150 in prophylaxis of migraine headache

Introduction: This study investigated the efficacy and tolerability of the highly selective iNOS inhibitor GW274150 in prophylaxis of migraine headache. Subjects and methods: The study was conducted in two parts, each comprising a 4-week baseline period, a 12-week, double-blind, parallel-group treatment period, and a 4-week follow-up period. The study had an adaptive design in that findings of Part 1 of the study were used to inform the conduct of Part 2. Following an interim analysis at the end of Part 1, the trial could be stopped for futility or continued in Part 2 to study the full-dose response or to increase sample size in case initial assumptions had been violated. The primary end-point in both parts of the study was the probability of the occurrence of a migraine headache day during the baseline period and the treatment period. Results: In Part 1, adult male and female patients with migraine received GW274150 60 mg (n = 37), 120 mg (n = 37), or placebo (n 38) once daily for 12 weeks. In Part 2, female patients with migraine received GW274150 60 mg (n = 160) or placebo (n 154) once daily for 12 weeks. GW274150 was no more effective than placebo for the primary efficacy end-point or any secondary efficacy end-point in Part 1 or Part 2. GW274150 was generally well tolerated. Conclusions: GW274150 at doses predicted to inhibit iNOS > 80% did not differ from placebo in the prophylaxis of migraine. The results do not support a role of iNOS inhibition in migraine prevention.