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Effect of High-Dose vitamin C on hepatic cytochrome P450 3A4 activity

van Heeswijk, R.P.G., Cooper, C.L., Foster, B.C., Chauhan, B.M., Shirazi, F., Seguin, I., Phillips, E.J. and Mills, E. (2005) Effect of High-Dose vitamin C on hepatic cytochrome P450 3A4 activity. Pharmacotherapy, 25 (12). pp. 1725-1728.

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Study Objectives. To investigate the effect of high-dose vitamin C on cytochrome P450 (CYP) 3A4 activity, and to evaluate possible sex-specific effects on CYP3A4 activity.

Design. Single-center longitudinal study.

Setting. Tertiary- and specialty-care teaching hospital.

Subjects. Fourteen healthy Caucasian adult volunteers (seven men, seven women).

Intervention. Subjects self-administered vitamin C 500 mg twice/day for 14 days.

Measurements and Main Results. Hepatic CYP3A4 activity was measured by using the erythromycin breath test on days 1 (baseline) and 15. Overall, no significant effect of vitamin C on CYP3A4 activity was observed. Sex and baseline results were significant predictors of changes in CYP3A4 activity. In men, mean activity increased by 21.9% (95% confidence interval −3.88–47.6%). The effect in women was not consistent.

Conclusion. Sex and baseline CYP3A4 activity appeared to influence the effect of vitamin C on CYP3A4 activity.

Item Type: Journal Article
Publisher: Wiley
Copyright: 2005 Pharmacotherapy Publications Inc.
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