An Update on Clinical Drug Interactions with the Herbal Antidepressant St. John's wort
St. John's wort (Hypericum perforatum, SJW) is one of the most commonly used herbal antidepressants for the treatment of minor to moderate depression. Limited clinical trials suggest that hypericum and standard antidepressants have similar beneficial effects, but current evidence regarding the antidepression effects of SJW extracts is inconsistent. A major safety concern about SJW is its ability to alter the pharmacokinetics and/or clinical response of a variety of clinically important drugs. This review highlights and updates the knowledge regarding drug interactions with SJW by a systematic review of all the available evidence, including worldwide published literature and spontaneous case reports. A number of clinically significant interactions of SJW have been identified with conventional drugs. These interactions often result in a decrease in the concentration or effect of the combined drug, most probably due to the induction of cytochrome P450s (CYPs) and the key drug transporter P-glycoprotein (P-gp) by the major active constituents in SJW. SJW is a potent inducer of human CYP3A4 and P-gp in vitro and in vivo. In addition, pharmacodynamic interactions of SJW with some drugs (e.g. selective serotonin re-uptake inhibitors) have been identified, which are associated with an increased risk of adverse reactions. Since potential interactions of SJW with conventional drugs is a major safety concern, it is important to minimize and avoid these interactions by taking appropriate approaches. These include systematic research to identify SJW-drug interaction; close therapeutic drug monitoring when SJW is combined with conventional drugs with a narrow therapeutic window; proper dose and regimen adjustment; patient education and communication between the patient and physician; design of new preparations of SJW without inducing ability of CYP3A4 and P-gp while retaining its bioactivity; and appropriate regulation in herbal safety and efficacy. Further clinical and mechanistic studies are warranted to explore the interaction of SJW with other important drugs and clinical significance.
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Document Type: Research Article
Publication date: June 1, 2008
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- Current Drug Metabolism aims to cover all the latest and outstanding developments in drug metabolism and disposition. The journal serves as an international forum for the publication of timely reviews in drug metabolism. Current Drug Metabolism is an essential journal for academic, clinical, government and pharmaceutical scientists who wish to be kept informed and up-to-date with the latest and most important developments. The journal covers the following areas:
In vitro systems including CYP-450; enzyme induction and inhibition; drug-drug interactions and enzyme kinetics; pharmacokinetics, toxicokinetics, species scaling and extrapolations; P-glycoprotein and transport carriers; target organ toxicity and interindividual variability; drug metabolism and disposition studies; extrahepatic metabolism; phase I and phase II metabolism; recent developments for the identification of drug metabolites and adducts.
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