Herb-drug pharmacokinetic interactions reviewed.
BACKGROUND
the global increase in the popularity of alternative medicines has raised renewed concerns regarding herb-drug interactions. These interactions are especially important for drugs with narrow therapeutic indices and may either be pharmacodynamic or pharmacokinetic in nature.


METHODS
pharmacokinetic interactions which may exist between herbs and drugs, and the mechanisms of these interactions with appropriate examples based on primary and secondary data in publications are discussed. The mechanisms covered include those that affect oral drug absorption (e.g., modulation of efflux and uptake transporters, complex formation, gastrointestinal motility and pH) and drug biotransformation (e.g., inhibition or induction of enzymes).


RESULTS
knowledge on the mechanisms of herb-drug pharmacokinetic interactions supported by an extended list of these types of interactions for quick reference. A critical evaluation of certain herb-drug pharmacokinetic interactions reported in the scientific literature.


CONCLUSIONS
as the incidence and severity of herb-drug pharmacokinetic interactions increase due to a worldwide rise in the use of herbal preparations, more clinical data regarding herb-drug pharmacokinetic interactions are needed to make informed decisions regarding patient safety.
Tshwane University of Technology, Department of Pharmaceutical Sciences, Pretoria, South Africa.
Clemence
C
Tarirai
Alvaro M
AM
Viljoen
Josias H
JH
Hamman
D000284:Administration, Oral; D000818:Animals; D001692:Biological Transport; D064420:Drug-Related Side Effects and Adverse Reactions; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000009:adverse effects; D005769:Gastrointestinal Motility; D041743:Herb-Drug Interactions; D006801:Humans; D006863:Hydrogen-Ion Concentration; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000378:metabolism*; D028321:Plant Preparations / Q000009:adverse effects / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D004364:Pharmaceutical Preparations; D028321:Plant Preparations