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Pharmacokinetic and pharmacodynamic interactions of echinacea and policosanol with warfarin in healthy subjects.

  • 2010-04-12
  • British journal of clinical pharmacology 69(5)
    • Mohi Iqbal Mohammed Abdul
    • Xuemin Jiang
    • Kenneth M Williams
    • Richard O Day
    • Basil D Roufogalis
    • Winston S Liauw
    • Hongmei Xu
    • Anita Matthias
    • Reginald P Lehmann
    • Andrew J McLachlan

Study Design

Type
Randomized Controlled Trial (RCT)
Sample size
n = 12
Population
12 healthy male subjects of known CYP2C9 and VKORC1 genotype
Methods
open-label, randomized, three-treatment, cross-over, clinical trial; single oral dose of warfarin alone or after 2 weeks of pre-treatment with each herbal medicine at recommended doses
Blinding
Open-label
Duration
2 weeks pre-treatment with each herbal medicine; single dose warfarin; cross-over with washout not specified
Funding
Unclear

Aims

This study investigated the pharmacokinetic and pharmacodynamic interactions of echinacea and policosanol with warfarin in healthy subjects.

Methods

This was an open-label, randomized, three-treatment, cross-over, clinical trial in healthy male subjects (n= 12) of known CYP2C9 and VKORC1 genotype who received a single oral dose of warfarin alone or after 2 weeks of pre-treatment with each herbal medicine at recommended doses. Pharmacodynamic (INR, platelet activity) and pharmacokinetic (warfarin enantiomer concentrations) end points were evaluated.

Results

The apparent clearance of (S)-warfarin (90% CI of ratio; 1.01, 1.18) was significantly higher during concomitant treatment with echinacea but this did not lead to a clinically significant change in INR (90% CI of AUC of INR; 0.91, 1.31). Policosanol did not significantly affect warfarin enantiomer pharmacokinetics or warfarin response. Neither echinacea nor policosanol had a significant effect on platelet aggregation after 2 weeks of pre-treatment with the respective herbal medicines.

Conclusion

Echinacea significantly reduced plasma concentrations of S-warfarin. However, neither echinacea nor policosanol significantly affected warfarin pharmacodynamics, platelet aggregation or baseline clotting status in healthy subjects.

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