[The effect of methotrexate on phenobarbital induction of monooxygenases and UDP-glucuronyltransferases in rat liver].

Methotrexate (N10-methyl-4-amino-4-deoxyfolic acid), administered to rats subcutaneously at a dose of 0.25 mg/kg within 14 days, was found to decrease content of microsomal protein in liver tissue and content of cytochromes P-450 and b5 as well as the drug decreased activity of amidopyrine- and ethylmorphine-N-demethylases, aniline-p-hydroxylase, UDP-glucuronosyltransferase and urinary excretion of glucuronides by 21%, 60%, 39%, 33%, 53%, 21%, 41% and 28%, respectively. Phenobarbital, administered subcutaneously at a dose of 60 mg/kg within 14 days, elevated the parameters by 28%, 187%, 63%, 163%, 162%, 100%, 95% and 60%, respectively. The effect of phenobarbital in combination with methotrexate was decreased by 77%, 49%, 55%, 52%, 43%, 42% and 22%, respectively.