[Benzodiazepines as cytochrome P-450 and cytochrome b5 inductors in rat liver microsomes]

Among the benzodiazepines tested (diazepam, oxazepam, clonazepam, nitrazepam and chlordiazepoxide ) chlordiazepoxide is the most potent inducer of cytochrome P-450, diazepam is a poor inducer, whereas clonazepam and nitrazepam do not possess a capacity to induce of cytochrome P-450. On the other hand, microsomal cytochrome b5 is induced by diazepam only. The extent of induction of cytochrome P-450 and cytochrome b5 depends on the environmental temperature. Chlordiazepoxide is the most potent inducer of cytochrome P-450 in rats exposed to an ambient temperature of 28 degrees C, whereas diazepam have the highest induction ability in rats exposed to 35 degrees C. On the other hand, nitrazepam increased the content of cytochrome b5 in rats exposed to temperature of 35 degrees C only; diazepam was the most potent inducer of cytochrome b5 in rats exposed to temperature of 21 degrees C. These results indicate that high ambient temperature is a factor modifying the ability of benzodiazepines to induce of microsomal cytochrome P-450 and cytochrome b5.