[Comparison of serum concentrations of caffeine, 4-methylaminoantipyrine, sulfamethazine and debrisoquin following oral administration of these substances as a cocktail in type II diabetics before and after insulin therapy].

A cocktail of 4 substances (caffeine/CYP1A/CYP1A2, metamizol/CYP2B, debrisoquin/CYP2D6 and sulfamethazine/N-acetyltransferase) was administered to 15 maturity-onset diabetics before and 6 months after insulin therapy (IT) to examine changes in hepatic biotransformation capacity in humans under pathological conditions. Blood and urine samples were taken 6 h after oral administration of the drugs. There were no differences in acetylation- and hydroxylationsphenotyping before or during IT. However, a significant increase in concentration of free sulfamethazine during IT can be interpreted as induction of N-acetyltransferase by poor metabolic control. Comparison of caffeine-concentration showed no significant differences. Obviously in humans CYP1A2 is not influenced by type-II-diabetes mellitus. Concentration of 4-methyl-antityprine (4-MAA), a metabolite of metamizol, was significantly increased during IT. This results shows a possible induction of CYP2B by poor metabolic control.