Factors influencing induction of hepatic microsomal drug-metabolizing enzymes.

Abstract The influence of some factors on the induction of the microsomal drug-metabolizing enzymes by phenobarbital was studied to obtain further information on the mechanism of induction. Only the administration of ethionine 30 min before the administration of phenobarbital completely inhibits the effect of phenobarbital. On the contrary, norleucine, p -fluorphenylalanine and methioninesulphoxide did not modify the effect of phenobarbital. An activator or an inhibitor were not found in the liver of the phenobarbital or the phenobarbital + ethionine pretreated rats. Treatment with phenobarbital can increase the enzyme activity also in rats which have low enzyme activities after administration of carbon tetrachloride and low dietary protein.