Transplacental passage of methicillin and dicloxacillin into the fetus and amniotic fluid

Abstract

The transfer of methicillin and dicloxacillin from maternal blood to fetal blood and amniotic fluid was studied in 105 patients. Significant levels of methicillin were detected in fetal serum within 30 minutes after discontinuing the maternal infusion, with equilibration between maternal and fetal serum levels within one hour. Dicloxacillin is associated with lower levels of antibiotic activity in the fetal serum and insignificant levels in the amniotic fluid. Equilibration between maternal and fetal levels did not occur. Protein binding of antibiotics results in a reduced rate of transfer from the maternal to the fetal compartment.