[Interaction in vitro of nicotinamide and diethylnicotinamid (cordiamine) with enzymes of the liver microsomal hydoxylating system in the rat].

Addition of nicotinamide and diethylnicotinamide (cordiamine) to rat liver microsomes leads to the formation of an enzyme-substrate Type II complex with cytochrome P-450. Diethylnicotinamide exceeded nicotinamide approximately 2-fold as regards the degree of the affinity to the enzyme. The ability of nicotinamide and diethylnicotinamide to interact with cytochrome P-450 underlies their antagonism with respect to in-vitro metabolism of the substrates of both Type I (amidopyrine) and Type II (aniline) as well as with respect to the competition with CO for the common center of binding on the enzyme.