[Determination of caffeine and metamizole elimination in pregnancy and after delivery as an in vivo method for characterization of various cytochrome p-450 dependent biotransformation reactions].

The elimination of caffeine from plasma and the elimination of the main metabolites of metamizol in urine were measured in 20 pregnant women, 19 puerperants, and 10 young healthy female non-pregnant volunteers. It was found a significant prolongation of caffeine elimination in pregnancy (t 1/2 = 9.4 +/- 0.6 h) with a correlation between duration of pregnancy and elimination half-life of caffeine (v = 0.72). The amount of the main metabolites of metamizol eliminated 0-9 h after application of the drug decreased from 82.6 +/- 8.2 mg in nonpregnant volunteers to 45.6 +/- 5.7 mg in pregnant women. Whereas caffeine elimination is restored within the first week after delivery, the rate of metamizol elimination does not reach the value of the non-pregnant volunteers in this period.