Destruction of cytochrome P 450 by secobarbital and other barbiturates containing allyl groups

Administration of certain commonly used barbiturates containing allyl groups, such as secobarbital, allobarbital, or aprobarbital to rats treated chronically with a microsomal enzyme inducer causes a rapid destruction of the liver microsomal hemoprotein that serves as the terminal oxidase for drug metabolism. In contrast, barbiturates without an allyl group do not have this effect. The decrease in this hemoprotein, cytochrome P(450), by the barbiturates containing an allyl group could also be demonstrated in an in vitro liver microsomal system requiring reduced nicotinamide adenine dinucleotide phosphate. These results suggest that the barbiturates containing an allyl group are converted to a metabolite that leads to the destruction of cytochrome P(450).