To describe long-term reductions in monthly migraine days (MMD) associated with acute treatment with rimegepant 75 mg.

Rimegepant, a small molecule CGRP receptor blocker, is approved as an acute treatment and has demonstrated benefits in migraine prevention.  Preventive benefits of PRN dosing on time to 30% and 50% reduction in MMDs are unknown.

The study population was derived from a multicenter, long-term (1 year), open-label safety study of rimegepant 75 mg oral tablet (NCT03266588). Eligible subjects included adults with ≥1 year history of migraine (ICHD-3 beta) who treated migraine attacks of any pain intensity with rimegepant 75 mg up to once daily as-needed (PRN) for up to 52 weeks. Kaplan-Meier analyses were used to assess median time to 30% and 50% MMD reduction in MMDs from baseline. Cluster analyses were used to identify 3 clusters based on baseline MMD.

Among 1,114 patients, the median (95%CI) time to a 30% reduction in MMDs was 8 (6-12) weeks and for a 50% reduction it was 20 (16-24) weeks. Among strata defined by baseline MMD, median time to 30% reduction was 8 (4-8) weeks for cluster 1 (8.1 MMD; n = 437), 12 (8-12) weeks for cluster 2 (10.4 MMD; n = 431), and 24 (24-36) weeks for cluster 3 (14.6 MMD; n = 246). Similar patterns of MMD change were observed for median time to 50% MMD reduction.

Repeated acute treatment of migraine with rimegepant 75 mg on a PRN basis, was associated with clinically relevant reductions in MMD without evidence of medication related increases in headache frequency.  These findings are consistent with preventive benefits of rimegepant 75 mg demonstrated in placebo controlled studies.