This open-label, single-center study investigated the kinetics of transfer of a single oral 75-mg dose of rimegepant into human milk.

Exposure of infants to medications can create an obstacle to optimal pharmacological migraine management in lactating women. Rimegepant is an oral, small-molecule, calcitonin gene-related peptide receptor antagonist with demonstrated efficacy and safety in the acute and preventive treatment of migraine.

Subjects were aged 18-40 years with a normal pregnancy (gestation 37-42 weeks) and uncomplicated delivery, of a single healthy child ≥2 weeks (14 days) but <6 months of age before rimegepant administration. Plasma samples were collected at 0, 1, 2, 4, and 8 hours after rimegepant administration. Breast milk samples were collected from both breasts and combined into a single sample before rimegepant dosing (time zero), and at 1, 2, 4, 8, 12, 16, 24, 32, and 36 hours after rimegepant administration. Rimegepant PK parameters in breast milk and plasma were determined using non-compartmental analysis and a population PK model, respectively. The milk to plasma drug concentration ratio was estimated as the breast milk:plasma area under curve ratio, which was used to determine infant dose. The relative (estimated) infant dose (%) was calculated as body weight normalized infant dose/body weight normalized maternal dose x 100.

Subjects (N=12) had a mean±SD age of 29.8±3.6 years and body mass index of 26.8±4.9 kg/m². The mean±SD relative infant dose was 0.51±0.14%; the median (range) was 0.46% (0.36, 0.77). The mean±SD body-weight normalized infant dose was 0.005±0.001 mg/kg/day, body-weight normalized maternal dose was 1.04±0.18 mg/kg/day, and maternal body weight was 74.0±13.3 kg.

On a weight-adjusted basis, the mean relative infant dose of rimegepant is less than 1% of the maternal dose. The results of this study will help inform the safe use of rimegepant by women with migraine during lactation.