Combined cancer chemotherapy with cyclophoshamide and an inducer of microsomal drug-metabolizing enzymes (cytochrome P-450) in tumor-bearing rats.

The fifty percent alive period in Yoshida sarcoma-bearing and AH66F-bearing rats was prolonged by an administration in a single dose of 100 mg cyclophosphamide/kg body weight in a group pretreated with phenobarbital as compared with that pretreated with saline. However, there was little difference in fifty percent alive period between AH109A (insensitive to cyclophosphamide)-bearing rats and controls even when they were pretreated with phenobarbital. In chemotherapy with anti-cancer drugs, inductive or inhibitory effects of the drugs on microsomal drug-metabolizing enzymes should be taken into consideration.