TIME-COURSE OF ETHYLENE THIOUREA IN MATERNAL PLASMA, AMNIOTIC-FLUID AND EMBRYOS IN RATS FOLLOWING SINGLE ORAL DOSING

Ethylene thiourea (ETU) was administered once orally to pregnant rats on gestation day 12 at a dose of 200 mg/kg, and its concentration-time courses in the maternal plasma, amniotic fluid and embryos were inves tigated. The ETU concentrations in the maternal plasma and amniotic fl uid reached the peak level about 2 hr after dosing, then declined grad ually and had disappeared by 48 hr. In embryos, the concentration of E TU peaked at 30 min after dosing and disappeared at 48 hr. The prolong ed exposure of the embryos to the high concentration of ETU in the amn iotic fluid could be partially responsible for the teratogenic effect of ETU.