Quantitative Assessment of Placenta Transfer of Fazadinium in Obstetric Anaesthesia

Fazadinium, 1 mg/kg, was administered to 16 women undergoing general anaesthesia for casearean section or vaginal delivery with forceps. Fazadinium serum levels were measured fluorimetrically in samples of maternal venous blood and umbilical arterial and venous blood obtained at the time of delivery. The umbilical to maternal ratio of venous fazadinium averaged 20% and was not influenced by the interval between induction and delivery. A lower concentration was found in the umbilical artery, and the arterial to venous cord blood concentration ratio was about 75% suggesting foetal drug uptake. In all cases, Apgar scores were normal at the fifth minute. It is concluded that there is a placental transfer of fazadinium; however, this transfer is limited and the risk of paralysis of the newborn appears unlikely after a single intubating dose of 1 mg/kg administered to the mother.