directed modification of the structure of cytochrome p450 substrates as a method of generating new inducers of the microsomal monooxygenase system using the previously obtained data on the substratetype induction of monooxygenase by xenobiotics of phenobarbital type the method of conversion of typical substrates for cytochrome p450 into inducers of biosynthesis of this enzymatic system by blocking in the substrate molecule of the position subjected to oxidative conversion in the enzyme active center was tested the introduction of the methyl group in the omega1 position of amobarbital of cl into positions 2 and 4 of biphenyl and the substitution of methyl groups for the isopropyl groups in the 4nch32 position of aminopyrine provides for marked induction of these derivatives of cytochrome p450 and some monooxygenase activities