Disposition of cefixime in the pregnant and lactating rat. Transfer to the fetus and nursing pup.

The disposition of cefixime, a potent, third generation, orally active cephalosporin, was characterized in the pregnant and lactating rat. After a single iv dose of 17.8 mg/kg 14C-cefixime to day 18 pregnant rats, the half-life for elimination of radioactivity from both maternal serum and placentas was 6.9 hr. Elimination from fetal plasma and tissues was somewhat longer, 12.5 and 13.7 hr, respectively. However, comparison of areas under the curve indicated that exposure of the fetuses to cefixime was far less than that of placentas. Whole body autoradiography showed the greatest radioactivity in maternal liver, kidney, and intestines. In the lactating rat, steady state plasma concentrations of 14C-cefixime were achieved by continuous ip infusion of 2.54 mg/kg/day via Alza osmotic Mini-pumps from days 10 to 14 postpartum. Plasma concentrations of radioactivity in the dams were, on the average, 70 times greater than in their nursing pups throughout the study. After 102 hr of drug infusion, total radioactivity in the body of the pups, including the stomach and intestinal contents, was 1% of the 14C-cefixime estimated to be in the mother's body at steady state. Overall, these data indicate that exposure of the developing rat fetus and nursing pup to cefixime after maternal drug administration is quantitatively small.