National Toxicology Program technical report series
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Natl Toxicol Program Tech Rep Ser · Nov 1993
Toxicology and Carcinogenesis Studies of 5,5-Diphenylhydantoin (CAS No. 57-41-0) (Phenytoin) in F344/N Rats and B6C3F1 Mice (Feed Studies).
5,5-Diphenylhydantoin and its sodium salt are primarily used in the treatment of grand mal and psychomotor seizures, often in combination with other anticonvulsants, including phenobarbital. 5,5-Diphenylhydantoin is a suspected human carcinogen and was one of three compounds selected by the NTP to investigate the potential value of perinatal exposures in assessing chemical carcinogenicity. Chronic toxicity and carcinogenicity studies of 5,5-diphenylhydantoin were conducted in male and female F344/N rats and B6C3F1 mice. The studies were designed to determine the following: a) the effects of 5,5-diphenylhydantoin in the diet given to rats and mice during the adult (F1) period only (a typical carcinogenicity study), b) the toxic and carcinogenic effects of 5,5-diphenylhydantoin in rats and mice receiving perinatal (F0) exposure only (dietary exposure of dams prior to breeding and throughout gestation and lactation), and c) the effects of combined perinatal and adult exposure to 5,5-diphenylhydantoin. ⋯ Combined Perinatal and Adult Exposure: Combined perinatal and adult dietary exposure to 5,5-diphenylhydantoin confirmed the findings of the increased incidences of hepatocellular neoplasms for adult-only exposures in male F344/N rats and female B6C3F1 mice, although combined exposure did not enhance these neoplastic effects. However, in male B6C3F1 mice, combined perinatal and adult exposure resulted in increased incidences of hepatocellular neoplasms (hepatocellular carcinomas and multiple adenomas) that were not seen when dietary exposure was limited to the adult exposure period only. Synonyms: Diphenylhydantoin; 5,5-diphenyl-2,4-imidazolidinedione Trade names: Difhydan; Dihycon; Di-Hydan; Di-Lan; Dilabid; Dilantin; Ekko; Hydantol; Lehydan; Zentropil