Presence of Hypnotics in the Cord Blood and Breast Milk, with No Adverse Effects in the Infant: A Case Report

Background: Hypnotics are frequently used for insomnia in pregnant and lactating women. This case study assessed zolpidem concentrations in the cord blood and breast milk and ramelteon concentrations in the breast milk of a woman who was treated with zolpidem and ramelteon for insomnia. Materials and Methods: Zolpidem concentrations were measured in maternal serum, breast milk, and cord blood. Concentrations of ramelteon and M-II, an active ramelteon metabolite, were measured in maternal serum and breast milk. Case Report: A 46-year-old female patient diagnosed with insomnia received 5-10 mg/day zolpidem during pregnancy and lactation and 8 mg/day ramelteon during lactation. A male infant weighing 3,329 g was born at 38 weeks' gestation, with no congenital abnormalities found during pregnancy or at birth. The infant was normal at the 1-month postpartum checkup. The maternal/placental ratio of zolpidem concentrations was 0.1 at 7.4 hours after maternal dosing, similar to that reported in previous studies. The calculated relative infant dose through breast milk based on the maximum drug concentration in breast milk at 2.2 hours after maternal dosing was 2.7% for zolpidem and 0.2% for ramelteon. Ramelteon and its metabolite (M-II) concentrations in the breast milk were equivalent to those in the maternal serum, although the infant exposure of these drugs was low for an oral dose. Conclusions: In the current case, zolpidem transferred into the placenta and breast milk, and ramelteon transferred into the breast milk. Further studies should assess the safety of zolpidem and ramelteon in fetus and breastfed infants.