Positive Health Online

Abstract

JIANG and colleagues, Faculty of Pharmacy, The University of Sydney, NSW2006, Australia, have investigated the effects of St John's wort and ginseng on the pharmacokinetics of warfarin in healthy subjects.

Background

The aim of the study was to examine the interactions of St John's wort and ginseng with warfarin.

Methodology

In this open-label, three-way crossover randomized study, 12 healthy male volunteers received a single 25 mg dose of warfarin , either alone, after 14 days of pre-treatment with St John's wort, or after 7 days pre-treatment with ginseng. Dosing with St John's wort or ginseng was continued for 7 days thereafter. Blood clotting parameters and the pharmacokinetics of warfarin were measured.

Results

Blood clotting parameters were not affected by either St John's wort or ginseng. However the catabolism and clearance of warfarin was enhanced by St John's wort but not by ginseng.

Conclusion

St John's wort induced a faster clearance of warfarin which in turn resulted in an apparent lessening of the pharmacological effect of the agent. Ginseng did not show any interactions with warfarin in this study.

References

Jiang X, Williams KM, Liauw WS, Ammit AJ, Roufogalis BD, Duke CCDay RO, McLachlan AJ. Effect of St John's wort and ginseng on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects. British Journal of Clinical Pharmacology 57 (5): 592-599, May 2004.