A comparison of the inductive effects of phenobarbital, methaqualone, and methyprylon on hepatic mixed function oxidase enzymes in the rat.

The effects of equal doses of three sedative-hypnotics, phenobarbital, methaqualone, and methyprylon, on the hepatic mixed function oxidase enzymes of the rat were investigated and compared. After 5 days of pretreatment, phenobarbital and methyprylon significantly increased aminopyrine demethylation, aniline hydroxylation, and cytochrome P-450 content in hepatic microsomes. Methaqualone pretreatment only increased hepatic aminopyrine demethylase activity and wet liver weights. After 29 days of pretreatment, phenobarbital significantly increases aminopyrine demethylase, aniline hydroxylase activity, liver weight and cytochrome P-450 content. Methaqualone only produced a significant increase in wet liver weight.