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Molecular mechanisms underlying St. John's wort drug interactions
Maike Kober1, Kerstin Pohl, Thomas Efferth
1Institute of Pharmacy and Molecular Biotechnology, Ruprecht Karls University, Heidelberg, Germany.
Current Drug Metabolism
|December 17, 2008
Summary
St. John's wort (SJW) can dangerously lower chemotherapy drug levels by activating liver enzymes. This review explores SJW's drug interactions and its potential in photodynamic therapy for cancer.
Area of Science:
- Pharmacology
- Oncology
- Herbal Medicine
Background:
- St. John's wort (SJW) is a popular herbal remedy with significant drug interaction potential.
- Concomitant use of SJW with conventional medications, especially chemotherapy, can lead to clinically relevant treatment alterations.
- Physician unawareness of SJW intake, due to its over-the-counter availability, exacerbates this issue.
Purpose of the Study:
- To provide molecular explanations for observed clinical drug interactions involving SJW.
- To focus on the impact of SJW on chemotherapeutic agents in cancer patients.
- To review novel applications of SJW-derived compounds in photophysical diagnosis and photodynamic therapy.
Main Methods:
- Literature review focusing on molecular mechanisms of SJW drug interactions.
- Analysis of studies investigating SJW's effect on drug-metabolizing enzymes and transporters.
- Detailed explanation of photophysical diagnosis (PPD) and photodynamic therapy (PDT) principles and mechanisms.
Main Results:
- SJW extract significantly reduces plasma levels of various anti-cancer drugs.
- This reduction is attributed to the activation of the pregnane X receptor (PXR), leading to the induction of CYP3A4 and P-glycoprotein.
- Hypericin, a component of SJW, shows promise for tumor localization via fluorescence and for cancer treatment as a photosensitizer in PDT.
Conclusions:
- SJW poses a significant risk of drug interactions, particularly for cancer patients undergoing chemotherapy.
- Understanding the molecular basis of these interactions is crucial for safe clinical practice.
- Hypericin-based PPD and PDT represent promising future therapeutic strategies in oncology.
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