Nicardipine in pre-eclamptic patients: placental transfer and disposition in breast milk

To assess the safety risks to the fetus and neonate caused by maternal use of nicardipine in pre-eclamptic patients, we evaluated the placental transfer and the transfer to breast milk after maternal intravenous administration of nicardipine. In ten pre-eclamptic subjects, nicardipine concentrations of maternal blood (P) and both arterial and venous umbilical cord blood samples (U-arterial and U-venous) were assessed, and the U/P ratio was calculated as an indication of placental transfer. We found a median transfer of 0.15 (U-arterial/P, range 0.05-0.22) and 0.17 (U-venous/P, range 0.023-0.22). The highest umbilical cord concentration found after maternal dosage of 4.5 mg/hour was 18 ng/ml, which can be considered as subtherapeutic. Therefore, adverse fetal reactions caused by a direct pharmacological effect of nicardipine are unlikely to occur. Nicardipine levels were determined in 34 breast milk samples of seven women, and were found to be undetectable in 82% of the samples. In six breast milk samples of four different women, nicardipine levels (ranging from 5.1 to 18.5 ng/ml) were detectable during maternal nicardipine dosages ranging from 1 to 6.5 mg/hour. The maximum possible exposure of a neonate to nicardipine was calculated to be less than 300 ng/day, which is an insignificant fraction of therapeutic dosages used in neonates. In conclusion, the exposure of a fetus and neonate to nicardipine through placental transfer and disposition in breast milk expression is low.