Intravenous dexmedetomidine for cesarean delivery and its concentration in colostrum

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.

Twenty-seven participants having elective cesarean delivery under combined spinal-epidural anesthesia were enrolled. After delivery and cord clamping, 6μg/kg/h of intravenous dexmedetomidine was administered for 10minutes, followed by a dose of 0.7μg/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 24h after dexmedetomidine administration. Samples were analysed using liquid chromatography tandem-mass spectroscopy.

Colostrum samples were collected from 10 patients. The median [95% CI] plasma dexmedetomidine concentration was 333 [303-534] pg/ml at 0h and 19.7 [13.5-25.8] pg/ml at 6h. The colostrum concentration was 12.3 [8.1-20.1] pg/ml at 6h. The dexmedetomidine completely disappeared from both within 24h. The calculated milk-to-plasma ratio at 6h 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.

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.