Placental and milk transfer of chloroquine in humans.
The placental and milk transfer of chloroquine was studied in seven subjects and six subjects, respectively. Seven pregnant women at term were administered chloroquine phosphate (5 mg/kg) i.m. The maternal blood and arterial and venous umbilical cord blood were obtained during delivery. The maternal chloroquine blood levels varied from 0.438 to 1.193 micrograms/ml. The venous cord blood ranged from 0.607 to 0.869, whereas the arterial levels ranged from 0.480 to 0.905 micrograms/ml. Six subjects who were administered chloroquine phosphate (5 mg/kg) postpartum had chloroquine milk levels of 0.192-0.319 micrograms/ml. The milk:blood ratio ranged from 0.268 to 0.462. Chloroquine readily crossed the placenta and was excreted into the breast milk.