[Determination of caffeine and metamizole elimination in men and women with and without hormonal contraceptives as an in vivo method for characterization of various cytochrome P-450 subspecies]. / Die Bestimmung der Coffein- und Metamizolelimination bei Männern und Frauen ohne sowie unter hormonalen Kontrazeptiva als in-vivo-Methode zur Charakterisierung verschiedener Cytochrom P-450 Subspezies.

Caffeine is mainly metabolized by 3-methylcholanthrene-inducible cytochrome P-450 (P-450MC) and noramidopyrine-methanesulfonate sodium (metamizol, Analgin) is mainly metabolized by phenobarbital-inducible cytochrome P-450 (P-450PB). We investigated the elimination of caffeine by the use of plasma concentration curves (HPLC) and the elimination of metamizol by spectrophotometric determination of the metabolites in urine in 10 healthy young males, in 10 healthy young females using no OL-steroids and in 10 healthy young females using OC-steroids. No influence of sex on the microsomal drug metabolism activity of these two drugs has been observed. There was a significantly decreased microsomal drug metabolism of both drugs in females under hormonal contraception. We conclude that OC-steroids decrease the demethylation activity of both P-450MC and P-450PB.