Effect of isoniazid on folic acid status in Swiss mice and rats.

Effect of isoniazid (INH) and its metabolites e.g. mono and diacetyl hydrazines (MAH and DAH respectively) was studied on circulating and tissue folates in mice (a species susceptible to INH tumorigenicity) and rats (a species resistant to INH carcinogenicity). It was observed that ip injection of INH, MAH and mydrazine sulfate (HS, 0.18 mg/g) decreased blood folates in mice while only HS and MAH decreased blood folates in rats. DAH had no effect on blood folates of mice or rats. Long term feeding of MAH and HS to mice decreased blood folates in treated mice at the age of 17 and 22 months respectively.