Transmission of Mepivacaine Hydrochloride (Carbocaine) Across the Human Placenta

Transmission of mepivacaine hydrochloride (Carbocaine) across the placenta was studied in 56 healthy women at term who received epidural analgesia during labor and delivery. All infants were delivered vaginally. Concentrations of mepivacaine were determined in maternal and umbilical cord blood by the methyl orange method. Mepivacaine administered into the maternal epidural space passed rapidly into the blood stream and crossed the placenta. Five mothers who received repeated injections, developed toxic symptoms; concentrations of the drug in blood were significantly higher than those in patients without complications. Twelve infants were depressed at birth; in 5, blood levels of the drug were significantly higher than those found in vigorous babies.