Intravenous dexmedetomidine for cesarean delivery and its concentration in colostrum

Background Dexmedetomidine is a sedative agent with high α₂-adrenoreceptor selectivity. We investigated intravenous dexmedetomidine administration during scheduled cesarean delivery under neuraxial anesthesia; and its concentration in the colostrum. Methods Twenty-seven participants having elective cesarean delivery under combined spinal-epidural anesthesia were enrolled. After delivery and cord clamping, 6 μg/kg/h of intravenous dexmedetomidine was administered for 10 minutes, followed by a dose of 0.7 μg/kg/h until peritoneal closure. Sedation, vital signs and side effects were recorded. Blood and colostrum samples were collected from each participant at 6, 12, and 24 h after dexmedetomidine administration. Samples were analysed using liquid chromatography tandem-mass spectroscopy. Results Colostrum samples were collected from 10 patients. The median [95% CI] plasma dexmedetomidine concentration was 333 [303–534] pg/ml at 0 h and 19.7 [13.5–25.8] pg/ml at 6 h. The colostrum concentration was 12.3 [8.1–20.1] pg/ml at 6 h. The dexmedetomidine completely disappeared from both within 24 h. The calculated milk-to-plasma ratio at 6 h was 0.76 [0.57–0.86]. The relative infant dose was 0.034% [0.020–0.062%]. At dexmedetomidine discontinuation, the Richmond Agitation–Sedation Scale score was −2 (range,−4 to −1). During surgery, no patients complained of nausea, peritoneal irritation or afterbirth pain. Conclusions The dexmedetomidine milk-to-plasma ratio did not exceed 1 in any participant, and the relative infant dose was very low. Maternal sedation using dexmedetomidine is unlikely to be harmful for the infant.