Fertility
Lemborexant was orally administered to female rats at doses of 30, 100, or 1000 mg/kg/day prior to and throughout mating and continuing to gestation Day 6. These doses are approximately 12 to >500 times the MRHD based on AUC. Irregular estrous cycles and decreased pregnancy rate were observed at 60 times the MRHD based on AUC, and decreased numbers of corpora lutea, implantations, and live embryos were observed at >500 times the MRHD based on AUC. The exposure at the NOAEL of 30 mg/ kg/day is approximately 12 times the MRHD based on AUC. Lemborexant did not affect fertility when orally administered to male rats at doses of 30, 100, or 1000 mg/kg/day prior to and throughout mating; the highest dose is approximately 138 times the MRHD based on AUC.
Carcinogenesis
Lemborexant did not increase the incidence of tumors in rats treated for 2 years at oral doses of 30, 100, and 300 mg/kg/day (males) and 10, 30, and 100 mg/kg/day (females), which are >80 times the MRHD based on AUC. Lemborexant did not increase the incidence of tumors in Tg ras H2 mice treated for 26 weeks at oral doses of 50, 150, and 500 mg/kg/day.
Mutagenesis
Lemborexant was neither mutagenic nor clastogenic in a standard battery of in vitro and in vivo genotoxicity studies.
Animal Toxicology and/or Pharmacology
Lemborexant administered to mice at oral doses of 10 or 30 mg/kg resulted in behavior characteristic of cataplexy when presented with chocolate. Chocolate is a stimulus that has been demonstrated to increase cataplexy occurrences in narcoleptic mice.