In vitro studies suggest that hypericin, a component of
St John's wort (Hypericum perforatum) may antagonise the
antineoplastic effects of
etoposide. It may also stimulate the
hepatic metabolism of
etoposide by CYP3A4.
Information is very limited but what is known suggests that it would be prudent to avoid St John's wort in patients taking
etoposide.