Clinical risks of St John’s Wort (Hypericum perforatum) co-administration

ABSTRACT

Introduction: St. John’s wort (SJW) is a common medicinal herb used for the treatment of mild to moderate depression. Hyperforin, one of the chief components of SJW, plays an important role in the induction of cytochrome P450 enzymes (CYP) and P-glycoprotein transporter (P-gp), and therefore, affects the pharmacokinetics of various drugs. There are several clinical studies demonstrating the interaction of SJW with the metabolism of conventional drugs which may cause life-threatening events.

Areas covered: This review focuses on human studies that have evaluated pharmacokinetic alterations of conventional drugs in concomitant use with different SJW preparations.

Expert opinion: SJW preparations have demonstrated clinically important interactions with several classes of conventional drugs such as immunosuppressants, anticancer agents, cardiovascular drugs, oral contraceptives, and lipid lowering agents that caused life-threatening events in several cases. The patient information label on the SJW products should provide enough information regarding the possible risk of interaction. Hyperforin seems to be the major ingredient responsible for CYP and P-gp inducing activity of SJW; thus, hyperforin-free products may be future candidates to decrease SJW’s drug interactions.

KEYWORDS:

• Herbal medicine
• St John’s wort
• drug interaction
• adverse drug reaction
• metabolism
• review

Article highlights

• The main mechanism by which SJW interacts with conventional drugs is the induction of cytochrome P450 isoenzymes and P-glycoprotein transporters.

• The major component of St. John’s wort (SJW) is hyperforin, that induces CYPs isozymes and P-gp.

• Immunosuppressants, cardiovascular drugs, chemotherapeutics, anticoagulants are examples of drugs which have serious interactions with SJW.

• Drugs which are not substrates for CYP and P-gp are less probable to show pharmacokinetic alterations with SJW coadministration.

• Low-hyperforin SJW extracts seems to show no interaction with drugs like digoxin, oral contraceptive, and cyclosporine.

• Patients receiving drugs with high probability of interaction with SJW should be warned not to self-medicate with any dosage form of SJW.

• Enough information regarding the possible risk of interaction and susceptible populations should be provided on patient information labels of SJW products.

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Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

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Funding

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