Probable Etoposide Interaction with Echinacea

Abstract

Echinacea is an herbal supplement commonly used as an immune system stimulant to prevent infections, such as the common cold or flu. Echinacea has been documented as a cyctochrome P450 (CYP) 3A4 inhibitor in vitro, but no formal studies have been conducted in humans. Etoposide is a cytotoxic, topoisomerase II inhibitor, chemotherapeutic agent used in the treatment of lung cancer. Etoposide is primarily metabolized by CYP 3A4. We report the first possible drug-herbal interaction between Echinacea and etoposide. A 61-year-old gentleman newly diagnosed with nonsmall cell lung cancer began concurrent chemoradiation with cisplatin and etoposide. He was admitted to the hospital on day 8 of his first cycle and found to be thrombocytopenic. His platelet count eventually reached a nadir of 16 × 10(3)/L, requiring platelet transfusion support. Upon admission, it was discovered he was taking Echinacea, which was discontinued. He received his next cycle of chemotherapy without taking Echinacea. His platelet count decreased to a nadir of 44 × 10(3)/L, but he did not require platelet transfusions. Echinacea likely contributed to this patient's profound thrombocytopenia and should be avoided in patients receiving etoposide and possibly other chemotherapeutic drugs that are CYP 3A4 substrates.

Chemotherapy in the elderly – How intense should treatment be?

“…Another publication points to probable interaction of etoposide with Echinacea [2]. In this case, it was likely that Echinacea contributed to a patient's profound life-threatening thrombocytopenia and therefore should be avoided in patients receiving etoposide and possible other chemotherapeutic drugs that are CYP 3A4 substrates.…”

Review and Assessment of Medicinal Safety Data of Orally Used Echinacea Preparations

“…Neither Echinacea nor policosanol significantly affected warafarin pharmacodynamics, platelet aggregation or baseline clotting status in healthy subjects [12]. Although details of drug administration, species, and type of extract are not stated, it is worth to mention a first report on a possible interaction between Echinacea and etoposide, a CYP3A4 substrate [13]. A 61-year-old man newly diagnosed with cell lung cancer began concurrent chemoradiation with cisplatin and etoposide.…”

“…The authors of the report concluded that since the exact preparation of Echinacea and corresponding plant extract constituents was unkown, the interaction remains equivocal. However, it has been written that cautions should be exercised in patients receiving chemotherapy including CYP3A4 substrates (antracyclines, etoposide, vinca alcaloids, taxanes) while taking Echinacea [3,13].…”

Potential risks associated with traditional herbal medicine use in cancer care: A study of Middle Eastern oncology health care professionals

“…15 The findings of this research are often contradictory, demonstrating either antagonistic effects, 16 additive effects, 17 synergy, 18 or no interaction whatsoever. 19 Clinical research has revealed several directly toxic effects of herbal products, 20,21 as well as alterations in the pharmacokinetics of anticancer drugs, 22 although these findings are often contradictory as well. 23 The conflicting findings with regard to herb-drug interactions have precluded the development of accepted guidelines.…”