Lemborexant is administered orally to pregnant rats during the period of organogenesis in 2 studies at doses of 60, 200, and 600 mg/kg/day or 20, 60, and 200 mg/kg/day, which are approximately 6 to >300 times the maximum recommended human dose (MRHD) based on AUC. Lemborexant causes maternal toxicity, manifests by decreased body weight and food consumption, decreases mean fetal body weight, an increased number of dead fetuses, and skeletal, external and visceral malformations (omphalocele, cleft palate, and membranous ventricular septal defect) at >300 times the MRHD based on AUC.
Lemborexant causes maternal toxicity that consisted of decreased body weight and food consumption and toxicity to offspring consisting of decreased pup body weights, decreases femur length, and decreases acoustic startle responses at 206 times the MRHD based on AUC. The no observed adverse effect levels (NOAEL) of 100 mg/kg/day is approximately 93 times the MRHD based on AUC.