Comparative teratogenicity of cortisone and phenytoin in mice

Single administrations of cortisone or phenytoin to pregnant mice on Days 11--14 of gestation caused similar skeletal and dissimilar soft tissue fetal anomalies. Cortisone reduced both maternal and fetal weight, whereas phenytoin only reduced fetal weight without adversely affecting maternal weight. A correlation between fetal weight reduction and cleft palate incidence was evident for each drug. Because probit analysis of dose--response regression lines did not deviate from parallelism after drug challenge, it was concluded that cortisone and phenytoin may produce palatal anomalies in the mouse fetus by a similar mechanism.