[Reproductive and developmental toxicity study of a new antineoplastic agent, S-1 (IV)--Perinatal and postnatal study in rats by oral administration].

S-1 is a newly developed antineoplastic agent consisting in a molar ratio of 1:0.4:1 mixture of tegafur (FT), 5-chloro-2, 4, dihydroxypyridine (CDHP) and potassium oxonate (Oxo) was administered orally to SD rats at doses of 0, 1, 4 and 7 mg/kg/day (as a dose of FT) during the perinatal and postnatal periods to examine its effect on dams and postnatal growth of the offspring. A group as the control was treated only with medium (0.5% hydroxypropyl methylcellulose) solution. The administration of 7 mg/kg/day to dams caused suppression in body weight gains and in food consumption during the treatment period. No adverse effects of S-1 on the length of gestation, gestation index, delivery and nursing ability were found. The administration of 4 and 7 mg/kg/day caused suppression in body weight gains in offspring of both sexes. Significant decrease in kidney weights were observed in females of the 4 mg/kg/day group and in both sexes of the 7 mg/kg/day group. No adverse effects of S-1 were found in number of live offspring at birth, sex ratio of live offspring, number of dead offspring at birth, birth index, viability index, weaning index, incidence of external anomalies, general conditions, postnatal development, reflex responses, motor coordination, emotional behavior, learning ability, skeletons, necropsy findings or reproductive functions. No adverse effects of S-1 on F2 offspring were found in any treatment groups. Under the conditions of the present study, the non-observed effect dose levels of S-1 was 4 mg/kg/day for general toxicology of dams, 7 mg/kg/day for reproductive ability of dams, 1 mg/kg/day for postnatal growth in F1 offspring and 7 mg/kg/day for postnatal growth in F2 offspring.