Authors: Yao Chen ChangQiong Xiao YiJing He BiLian Chen Guo Wang Gan Zhou Wei Zhang ZhiRong Tan Shan Cao LiPing Wang HongHao Zhou
Publish Date: 2010/12/14
Volume: 67, Issue: 4, Pages: 347-353
Abstract
A single dose of 100 mg caffeine was administered once before and once on the last day of a 14day treatment regime with 1 g genistein once daily to 18 healthy female volunteers Urine and blood samples were collected up to 12 and 24 h respectively after each caffeine dose Using highperformance liquid chromatography HPLC caffeine and 17dimethylxanthine 17X were quantified in plasma whereas 17X 17dimethylurate 17U 1methylxanthine 1X 1methylurate 1U and 5acetylamino6formylamine3methyluracil AFMU were quantified in urine Urinary metabolite ratios were calculated to assess enzyme activities and compared between administrations using analysis of variance ANOVAGenistein decreased the urinary caffeine metabolite ratio used to assess CYP1A2 activity by 41 90 confidence interval CI 28–51 The urinary ratio indicating XO activity decreased by 29 90 CI 24–32 whereas urinary ratio for CYP2A6 activity increased by 47 90 CI 29–66 after 2 weeks of genistein The NAT2 urinary caffeine metabolite ratio did not change significantlyTwo weeks of intake of 1 g genistein daily led to decreases in CYP1A2 and XO activity and an increase in CYP2A6 activity whereas NAT2 activity did not change in healthy Chinese female volunteers Pharmacokinetics of other substrates of the enzymes investigated here may be influenced in a similar manner
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