Abstract
1. 14C-Captopril (50mg/kg) administered orally to pregnant rats resulted in radioactivity passing the placental barrier into foetuses and amniotic fluid. Two hours after dosing, the mean (± S.E.M.) concentration of total radioactivity was 0.97 ± 0.07 μg equiv. of captopril/g in foetuses and 7.8 ± 0.54 μg equiv./g in maternal blood. The mean concentration of unchanged captopril at this time was 0.22 ± 0.04 μg/g in foetuses and 2.4 ± 0.27 μg/g in maternal blood. Results obtained by whole-body autoradiography generally were consistent with those obtained by measuring radioactivity in excised tissues.
2. Radioactivity was also found in suckling pups and in the milk of the dams. Autoradiographs of the pups showed detectable radioactivity in the brain; as no radioactivity was detectable in the brain of the dam, it appears that the blood-brain barrier was not fully developed in seven-day-old pups.