Standardization of TCM Herbs
Several speakers from academic centers, including the University of Hong Kong and the Macau University of Science and Technology, presented an overview of the techniques to examine herbal preparations in reference laboratories. These methods were standard methods of high-performance gas and liquid chromatography. Of interest was the use of gene chips to examine patterns of RNA expression in cells exposed to herbal fractions and the application of bio-informatic methods to assess gene expression. These methods have been recently reported in the United States for certain Chinese herbs. 24]
The first step in the preclinical study of herbs must be a reliable and standardized classification of herbs based on their biochemistry to assess toxicity of the herb in the absence of contaminating substances.[21,25] Elegant throughput screening of herbal compounds in a collagen-induced model was presented by Professor A. Lu of the China Academy of Traditional Medicine in Beijing. Using a similar model, a novel botanical product ("QFJS") was reported by Dean L. Liang of Hong Kong University. At a time when the number of candidates for small molecules that may provide new direction for therapy appears small, the evaluation of new classes of flavonoids and alkaloids derived from herbs may provide a new avenue for modulating the immune system. The analogy would be Taxol, initially isolated from bark, and then synthesized to allow chemical isomers to be developed.
Prof. Leung Ting Hung, Deputy Director of Health in Hong Kong, pointed out that "in 1999, a statute was enacted that applied to manufacturing and dispensing herbs. This statute requires manufacturing standards, licensing, and education of persons dispensing the herbs. The time has now come to implement those standards and the Hospital Authority is using information technology methods to assure quality control and compliance." Dr. Jin Dou of the FDA in the United States noted that as of June 2005, more than 250 botanical preparations had been applied for licensure in the United States. Regulatory guidelines for manufacturing and contamination are currently being implemented and the availability of standardized herbs will allow more optimal monitoring. However at present, there is little regulation of the herbs that are sold as supplements to the general consumer. However, the FDA (CDER) hopes to implement a program of toxicology for regular review and evaluation to include over the counter products. Dr. S. Lam of the UK described a new European Directive on Traditional Herbal Medicines to take effect in October 2005. It is hoped that the directive will take the eventual form of legislative enactment with enforcement. Certainly, the plan for standardization outlined by Hong Kong will serve as a guideline. In comparison, Dr. Patrick Choy of Canada noted that the Food and Drug Act in Canada does not evaluate claims. In 2003, the National Health Service outlined a plan for licensing botanical products, but a grace period of 6 years was granted for implementation.
The need for international regulation of herbal products and proposed regulations were presented by Drs. J. Dou of the US FDA, S.P. Lam of the Healthcare Products Regulatory Agency (MHRA) of UK, P. Choy from Canada, H. Cranz of Belgium (Director, Association of Self Medication Industry), and S. Behjat of United Arab Emirates. There was similar expression by experts in pharmacology and drug regulation from other countries of the need for uniform nutriceutical preparation.
A series of presentations addressed the concern of western medicine that herbal content is often variable among manufacturers due to lack of standardization. This has been dramatically observed among ginseng products. In a study, it was shown that 4 of 17 valerian products tested had no detectable levels of the expected valerianic acids, while another 4 had only 50% of the expected amount. Even when herbal preparations are labeled "standardized," there may still be significant variability. For example, one study of echinacea found that the content did not match the labeling in 47% of samples labeled "standardized." Generally, higher price predicts better consistency with a benchmark.
The strength of a plant's pharmacologic activity may also vary in accordance to where it was grown, when it was harvested, and the time it was stored. Plant products and their active constituents can vary like wines from year to year due to climatic changes involving rainfall, sunlight, and even genetic composition. These factors impact the ability to insure standardization of herbal products. Patients should be advised that currently there is no definitive methodology of assuring that herbal content will not vary from one product to another, or even from one batch to another.[4,17]
Several pharmaceutical companies have begun marketing standardized preparations of herbal extracts. While these newer products provide a much higher grade and relatively "predictable" response that physicians can recommend to their patients, they paradoxically raise a number of controversial issues for patients who want a "natural product." For these patients, it is not clear whether these products represent herbs or are actually new pharmaceutical agents. Thus, for the pure herbalists, these extracts and pharmaceutical productions may be regarded as "drugs" because they do not use the entire plant with all of its constituents.[4,17] An additional challenge to standardization and use is the "misuse" of herbal medications, as exemplified by the recent removal from market of ephedra. This herbal extract was used for treatment of asthma in TCM rather than the higher doses used in the west for weight reduction.[4,17] Despite these challenges, this pharmacologic approach to standardization and the development of databases may ultimately answer questions about relative efficacy and safety.
Medscape Rheumatology. 2005;7(2) © 2005 Medscape
Cite this: Highlights of the International Conference and Exhibition of the Modernization of Traditional Chinese Medicine and Health Products - Medscape - Sep 15, 2005.