Inhibition of caffeine metabolism by estrogen replacement therapy in postmenopausal women.

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Pollock BG, Wylie M, Stack JA, Sorisio DA, Thompson DS, Kirshner MA, Folan MM, Condifer KA

Inhibition of caffeine metabolism by estrogen replacement therapy in postmenopausal women.

J Clin Pharmacol. 1999 Sep;39(9):936-40.

PubMed ID

10471985 [ View in PubMed

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Abstract

This study was conducted to investigate the effect of therapeutic estrogen on cytochrome P450 1A2-mediated metabolism in postmenopausal women using caffeine as a model substrate. Twelve healthy postmenopausal women underwent estrogen replacement therapy in the form of estradiol (Estrace). Estradiol was initiated at a dose of 0.5 mg a day and titrated to achieve a steady-state plasma concentration of 50 to 150 pg/ml. Caffeine metabolic ratios (CMR; paraxanthine/caffeine) were assessed both before and after 8 weeks of estrogen replacement. For the 12 subjects, there was a mean reduction in CMR of -29.2 +/- 25.0 (p = 0.0019). Consistent with previous results found in younger women, these results indicate that exogenous estrogen in older women may inhibit CYP1A2-mediated caffeine metabolism.

DrugBank Data that Cites this Article

Drug Enzymes

Drug	Enzyme	Kind	Organism	Pharmacological Action	Actions
Estradiol	Cytochrome P450 1A2	Protein	Humans	Unknown	Substrate Inhibitor	Details
Estradiol cypionate	Cytochrome P450 1A2	Protein	Humans	Unknown	Substrate Inhibitor	Details