Placental transfer of radioactive digitoxin in pregnant women and its fetal distribution.

Placental transfer of radioactive C-digitoxin was investigated in four pregnant women. The concentration of the labeled drug and its metabolic products in the various fetal organs was determined. Less than 1 per cent of the administered glycoside was detected in the fetus as unchanged digitoxin and less than 3.5 per cent as its metabolites. The fetal heart and kidney of 11 to ]2 weeks gestation had the highest concentrations. However, at near term the fetal liver, gallbladder and intestine had somewhat similar concentrations. Metabolic conversion of the cardiac glycoside by fetal liver as well as biliary excretion is indicated from the tissue distribution data.