A study of the kinetics of cephapirin and cephalexin in pregnancy.

The kinetics of cephapirin and cephalexin were studied in 60 pregnant women after the administration of single 1 g doses of the antibiotics given by the intramuscular and oral route, respectively. Maternal serum, amniotic fluid and cord serum concentrations were measured at intervals after the dose by the agar diffusion method. The results showed that the mean peak concentration of cephalexin in maternal serum, after 1 hour, was significantly greater than that of cephapirin. Both antibiotics crossed the placenta barrier and reached levels in the amniotic fluid and cord serum adequate for the in vitro inhibition of pathogens involved in materno-foetal infections.