Review articleTraditional Chinese medicine: an approach to scientific proof and clinical validation
Introduction
There are two powerful new trends in the development of novel pharmaceuticals. Biotechnology is generating a new class of biological therapeutics and providing a novel approach to rational drug design. At the same time, there has been a growing interest in alternative medicine, particularly the use of herbal products. Modern drugs in the form of single-chemical entities have been successful in the treatment of acute conditions such as infectious diseases. Drug action is fast and predictable, leading to a favorable resolution of a critical situation in a short period of time. The situation is markedly different when treating chronic conditions such as asthma and hypertension. The course of treatment typically does not provide a cure, but an alleviation of symptoms. This requires that the patient receive the drug(s) for a long and indefinite period of time. The treatment can also result in serious side effects, particularly in the long term.
While many modern drugs originated from plants, unpurified herbal preparations are used extensively in both Europe and Asia. Western herbal medicines are often standardized extracts of single herbs used for particular conditions. For example, valerian and St. John's wort are used for sleep aid and mild depression, respectively. In comparison, traditional Chinese medicines (TCMs) are decoctions of mixtures of up to 20 herbs that are customized for each individual patient. TCMs represent one aspect of Chinese medical philosophy that is characterized by its emphasis on maintaining and restoring balance. This medical approach is much more appropriate to disease prevention and the treatment of chronic diseases without an unacceptably high level of collateral damage.
Most Chinese formulations contain a mixture of herbs. There are different methods of classifying the ways in which these can be combined. When combined, two biologically active substances can be observed to have the following effects: mutual accentuation, mutual enhancement, mutual counteraction, mutual suppression, mutual antagonism, and mutual incompatibility. The principal ingredient is a substance that provides the main therapeutic thrust, the second principal ingredient enhances or assists the therapeutic actions of the first. The rest serve one of the following functions: treat accompanying symptoms, moderate the harshness or toxicity of the primary ones, guide the medicine to the proper organs, or exert a harmonizing effect.
Most Westerners do not take TCM seriously, considering it unscientific in its understanding of the human body and the nature of disease and its treatment. The adoption of TCMs in industrialized countries is impeded by a lack of quality control and the absence of scientific and clinical proof of their effectiveness. A recent editorial in JAMA emphasizes that the fundamental issue is not traditional medicine versus alternative medicine, but medical practice supported by clinical and scientific evidence (Fontanarosa & Lundberg, 1998).
In this review, we show how TCMs differ from therapeutics based on single-chemical entities, and outline how modern scientific and clinical procedures need to be adapted for the study of such herbal preparations. The studies cited (all drawn from the English language literature) show that when properly done, modern techniques can provide valuable information for the validation of specific TCMs, particularly in the prevention and treatment of chronic diseases.
Section snippets
Characterization of complex formulations
The National Cancer Institute (Bethesda, MD, USA) and the United States Department of Agriculture have screened 35,000 samples of roots, fruits, and bark from 12,000 plant species. This laborious effort resulted in the discovery of only three new drugs. On the other hand, the ancient pharmacopoeias of China and India contain thousands of therapeutic formulations. How does one reconcile these different sets of results? One likely explanation is that the biological activities of such preparations
Chemical profiles and biological assays
There is a considerable body of information on the chemical composition of Chinese herbs, although most of it has been published in Chinese and Japanese journals. In some cases, purified compounds are then studied in vitro or in animal models to correlate the presence of certain chemicals with physiological effects on humans. One of the most extensively studied Chinese herbs is ginseng (Panax ginseng), which contains 2–3% ginsenosides (triterpene saponins). The main ginsenosides are Rg1, Rc,
Clinical trials
Chemical analyses, biological assays, and animal experiments provide important fundamental information about specific TCM formulations. In the context of modern biomedical research, they should also be necessary prerequisites for clinical trials. Most of these TCM clinical trials have been undertaken in China, Taiwan, and Japan, and more often than not, both the protocols and results are unavailable in the English-language medical literature. In addition, most of them do not follow the
Conclusion
The principal objective of the study of Chinese herbal formulations is to determine whether they may represent a platform for the development of novel therapeutics. This is not a simple exercise of applying modern technologies and clinical designs to products that have been in constant use for centuries. Western and Chinese medical practices represent totally different philosophies towards human health. Western medicine has methodically looked at the relationship between structure and function
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