Evaluation of literature on the toxicity of Chinese herbal medicines

Article type
Authors
Drew A, Bensoussan A, Dawson A, Whyte I, Myers S
Abstract
Introduction/Objective: Complementary medicine use is increasing and it is estimated that importation of raw and proprietary Chinese medicines into Australia has grown four-fold since 1992. Adverse drug reaction (ADR) reports to Chinese herbs continue to be published indicating their toxicity is not well defined despite centuries of use. The aim of this project is to systematically review European, Chinese, Korean and key Japanese literature on toxicity of 300 known toxic or commonly used Chinese herbs, to grade the toxicity of these herbs and strength of evidence for toxicity and consolidate information into a database for use by government departments, drug information centres and other bodies. The initial stage involves reviewing English language literature from biomedical databases.

Methods: Medline, Embase (Drugs and Pharmacology), Iowa Drug Information Service and Biological Abstracts databases are being searched for citations on a few herbs and their pharmacological constituents using a wide search strategy.

Results: Preliminary database searching has confirmed the need to employ a wide search strategy and cull from large numbers of citations. With the exception of Embase Drugs and Pharmcology, which indexes many plant names and constituents, other databases require freetext searching. Relevant citations in English language literature take the form of in vitro studies, animal studies, often based on isolated plant constituents, and ADR case reports/series, which are the only type of literature directly relating to humans retrieved so far.

Discussion: It may not be possible to refine the search strategy due to the lack of systematic indexing of botanical names of Chinese herbs in biomedical databases. Application of in vitro and animal studies to human safety and relevance of toxicity studies on separate pure forms of pharmacological constituents pose a challenge because of the way Chinese herbal medicines are used (generally in combination). Analysis of the Chinese herbal medicine implicated as a cause of ADRs is essential to exclude product quality issues (adulteration with synthetic drugs, substitution with another plant species, contamination with eg. heavy metals) from inherent safety of the Chinese herb.