1.2.5 Clinical Studies of Herbal Medicines
Anything that exists on the earth has a need for survival. Many traditional herbs have been used on human beings to prevent and treat diseases for hundreds or even thousands of years. The fact should be acknowledged that most of the herbs have been used by countless people. Take Chinese herbal medicine as an example. The efficacies, toxicities, therapeutic and toxic dosages, as well as cautions and contraindications of most herbs have been well recorded in many traditional Chinese herbal books. Although the terminologies used for diagnosis and treatment of diseases in traditional and modern medicines are different, researchers are encouraged to figure out the symptoms described in traditional terminologies for the application of traditional medicine and try to match them to that of modern diseases for scientific clinical trial.
A successful clinical trial depends on accurate scientific design. In comparison to the trial for a single chemical drug, that for an herbal product is more complicated due to the complex composition and difficult quality control of the components. The extract method, the concentrations of the main or bioactive compounds in the products (or the purity of the products), the number and criteria of patients selected, the route and dosage of the administration, the period of the trial, and the method to collect and process the data will all influence the results of the trial.
Unfortunately, many of the reported results of clinical studies on herbal medicine so far are not reliable due to more or less unscientific design. Quite often, the results of clinical trial for one herbal medicine obtained by different research groups vary significantly. A well-known example is St. John’s Wort. Some reported this herb to have an effect on mild depression; others reported no such effect. Possible reasons have been mentioned in the above paragraph. A difference in any step of the experimental design will affect the result.
To obtain reliable clinical trial results for herbal medicines, double-blind experiments should be applied with enough patients selected, ideally using the standard of clinical trial for new drug development. Of course, budgetary constraints are often a hindrance to carrying out such trials.
Soure: Traditional Herbal Medicine Research Methods, Edited by Willow J.H. Liu Copyright © 2011 John Wiley & Sons, Inc.
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