A method to obtain maternal-fetal plasma samples using a microsampling technique in the rat: transplacental passage...

A microsampling technique that allows taking blood samples from the umbilical vein of the pregnant rat is described. Such techniques are needed in order to allow pharmacokinetic and embryo exposure to be correlated with teratogenic endpoints. Cefoxitin was administered intravenously (300 mg/kg) into tracheotomized, pentobarbital anesthetized dams on day 21 in gestation. Blood samples were collected via the carotid artery from the dam and the umbilical vein of the fetus at designated times. Up to three samples of 20 to 30 microliters each, were taken from individual fetuses at 20-min intervals. With few exceptions, fetal cefoxitin concentrations were homogeneous at each sampling period. Fetal concentrations were low compared to maternal concentrations as seen by the small fetal/maternal area under the curve ratio (0.053 +/- 0.006).