The effect of Echinacea purpurea on the pharmacokinetics of docetaxel

AIMS: The herbal medicine Echinacea purpurea (E. purpurea) has been shown to induce cytochrome P450 3A4 (CYP3A4) both in vitro and in humans. This study explored whether E. purpurea affects the pharmacokinetics of the CYP3A4 substrate docetaxel in cancer patients. METHODS: Ten evaluable cancer patients received docetaxel (135 mg, 60 min IV infusion) before intake of a commercially available E. purpurea extract (20 oral drops three times daily) and 3 weeks later after a 14 day supplementation period with E. purpurea. In both cycles, pharmacokinetic parameters of docetaxel were determined. RESULTS: Before and after supplementation with E. purpurea, the mean area under the plasma concentration-time curve of docetaxel was 3278 +/- 1086 and 3480 +/- 1285 ng ml(-1) h, respectively. This result was statistically not significant. Nonsignificant alterations were also observed for the elimination half-life (from 30.8 +/- 19.7 to 25.6 +/- 5.9 h, P = 0.56) and maximum plasma concentration of docetaxel (from 2224 +/- 609 to 2097 +/- 925 ng ml(-1) , P = 0.30). CONCLUSIONS: The multiple treatment of E. purpurea did not significantly alter the pharmacokinetics of docetaxel in this study. The applied E. purpurea product at the recommended dose may be combined safely with docetaxel in cancer patients.