[A comparative study of the effects of nicotinamide and diethylnicotinamid on hepatic monooxygenase, glucuronyl and glutathione conjugating systems].

The nicotinamide administration to rats (50 mg/kg, subcutaneously, over 5 days) increased the concentration of liver cytochrome b5, the activities of cytosol and microsomal glutathione S-transferase, UDP-glucuronosyltransferase and urinary excretion of bound glucuronic acid by 26.7, 33.1, 33.3, 53.0 and 31.0%, respectively. The chloral hydrate-induced sleep time in mice was reduced by 65%. Under similar experimental conditions the administration of equimolar amounts of diethylamide of nicotinic acid (75 mg/kg) exerted a more pronounced enzyme-stimulating effect. The cytochrome P-450 concentration, the activities of cytosol and microsomal glutathione S-transferase, UDP-glucuronosyltransferase as well as the sulphobromophthalein elimination from blood plasma and urinary excretion of bound glucuronic acid were increased by 37.0, 33.1, 54.6, 80.5, 24.5 and 49.0%, whereas the chloral hydrate-induced sleep time decreased by 75%. The nicotinamide and diethylamide of nicotinic acid stimulating effects on xenobiotic biotransformation in rat liver are assumed to be due to enhanced NADPH, glutathione and UDP-glucuronic acid biosynthesis as well as their antioxidant properties.