Assess the effects of rimegepant 75 mg on monthly migraine days (MMDs) through 52 weeks of open-label treatment when dosed  every other day (EOD) plus as-needed (PRN) on nonscheduled dosing days.

This open-label extension phase of a 12-week, phase 2/3, randomized, double-blind, placebo-controlled study evaluating rimegepant 75 mg EOD for preventive treatment of migraine included adults aged ≥18 years with a history of 4-18 moderate to severe monthly migraine attacks. Subjects completing the 4-week observation period and 12-week double-blind treatment period could continue with open-label rimegepant 75 mg EOD for preventive treatment of migraine for 52 weeks. On nonscheduled dosing days, subjects could take rimegepant 75 mg up to once per day PRN for acute treatment. This analysis assessed the effects of rimegepant on the mean change from the observation period in MMDs and the percentages of subjects with ≥50%, ≥75%, or 100% reductions from the observation period in moderate-severe MMDs. Months were defined as 4-week intervals.

The mean (95% CI) changes from the observation period in MMDs were −5.1 (−5.49, −4.74) in Weeks 1-4 and −6.9 (−7.31,−6.56) in Weeks 49-52. The percentage of subjects with ≥50% reduction in moderate or severe MMDs from the observation period ranged from 63.6% in Weeks 1-4 to 80.9% in Weeks 49-52, ≥75% reductions ranged from 44.1% in Weeks 1-4 to 65.8% in Weeks 49-52, and 100% reductions ranged from 25.6% in Weeks 1-4 to 49.3% in Weeks 49-52.