Prevention Study in Adult Patients Suffering From Migraine Headaches

MPX111381 is a multicenter, randomized, double-blind, placebo-controlled, parallel group, flexible-dose evaluation of GSK1838262 1200 mg/day, 1800 mg/day, 2400 mg/day and 3000 mg/day compared with placebo in the prophylactic treatment of migraine headache. Subjects 18 years of age must have experienced at least three migraine headache attacks (with or without aura according to 2004 International Headache Society \[IHS\] criteria 1.1 and 1.2.1) per month during the 3 months prior to screening and at least four migraine headache days but less than 15 total headache days (migraine or non-migraine) per month during the 3 months prior to screening and must maintain this requirement throughout the last 4 weeks of the baseline period. Approximately 528 subjects from approximately 53 centers in North America will be randomized in a 2:1:2:2:1 ratio to the following treatment groups: placebo, GSK1838262 1200 mg/day, 1800 mg/day, 2400 mg/day and 3000 mg/day. Investigational product will be administered twice daily (morning and evening) with food (e.g., meal or snack). The study will consist of six study periods for a total study duration of up to 30 weeks: Screening (2 weeks), baseline (including randomization, 6 weeks), flexible titration (5 weeks), maintenance (12 weeks), taper (3 weeks) and post-treatment (2 weeks). The flexible titration administration of investigational product is designed to allow subjects to reach the target dose for maintenance treatment or, if unable to reach this target dose, to achieve a maximum tolerated dose for maintenance treatment. Subjects will have the opportunity to undergo a single dose (600 mg/day) downward adjustment during the flexible titration period if intolerability at the current dose occurs. Subsequently, if a single dose downward adjustment has occurred, no further dose adjustments in the study (upward or downward) will be permitted.