Planta Med 2004; 70(9): 784-791
DOI: 10.1055/s-2004-827223
© Georg Thieme Verlag KG Stuttgart · New York

Pharmacokinetic Herb-Drug Interactions: Are Preventive Screenings Necessary and Appropriate?

Veronika Butterweck1 , Hartmut Derendorf1 , Wilhelm Gaus2 , Adolf Nahrstedt3 , Volker Schulz4 , Matthias Unger5
  • 1Department of Pharmaceutics, University of Florida, Gainesville, FL, USA
  • 2Abteilung Biometrie und Medizinische Dokumentation, Ulm, Germany
  • 3Institute of Pharmaceutical Biology and Phytochemistry, Münster, Germany
  • 4Berlin, Germany
  • 5Institut für Pharmazie, Würzburg, Germany
Further Information

Publication History

Received: June 14, 2004

Accepted: July 12, 2004

Publication Date:
23 September 2004 (online)


Pharmacokinetic interactions often occur as a result of activity changes of drug-metabolizing and transporting proteins, especially cytochrome P450 (CYP) isoenzymes and P-glycoprotein (P-gp). The activity of these enzymes and drug transporters can be enhanced or inhibited by synthetic drugs as well as by natural products. Since the number of herb-drug interactions has increased in recent years, systematic in vitro screenings and more clinical studies to identify such interactions were proposed for herbal medicinal products. However, previous results regarding this issue are not only contradictory but also of less predictability. One reason for the discrepancies could be the lack of validation of the recommended in vitro tests. Furthermore, it has to be considered that pharmacokinetic drug interactions are not only mediated by herbal medicines but also by several foods, beverages and life-style products. Since herbal medicines are considered to have a broad therapeutic range, a preventive risk assessment for pharmacokinetic drug interactions should first be realized for synthetic drugs with a narrow therapeutic index. Efforts to identify all possible interactions will lead to limitless investigations and to inconsistent decisions.


Prof. Dr. med. Volker Schulz

Oranienburger Chaussee 25

13465 Berlin