VOLUME 26 : NUMBER 6 : December 2003
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Modern chemical and pharmacological research has greatly contributed to our understanding of Chinese medicine. The quality of Chinese medicines may be controlled by understanding their pharmacognosy and applying pharmaceutical methods. Chinese medicines may have intrinsic toxicity. They can also be contaminated and adulterated. Interactions with prescription drugs are also possible. Regulation, backed by education and research, is needed to improve the quality and quality use of traditional Chinese medicines.
Key words: complementary medicines, herbal preparations, pharmacognosy.
Aust Prescr 2003;26:128-30
Traditional Chinese medicine is a medical system based on theory, pathology, diagnosis, treatment and herbal pharmacology principles that differ from those of orthodox medicine or Western naturopathy. The practice of traditional Chinese medicine has developed from knowledge accumulated through clinical observation and treatment over several millennia. Traditional Chinese medicine has an established history in Australia and has expanded rapidly in recent years. Chinese medicines now account for 3.2% of the total use of complementary medicines.1 The Chinese Medicine Registration Act was approved by the Victorian Parliament in 2000, to regulate the qualifications of traditional Chinese medicine practitioners and dispensers to encourage the safe use of traditional Chinese medicines in Victoria.
In parallel with the growth of Chinese medicine, serious issues have been raised about its quality and safety in Western countries. Chinese medicines have been contaminated with toxic heavy metals and adulterated with prescription drugs.2There is therefore a need for quality assurance of Chinese medicines in Australia.
Active principles and therapeutic effects of Chinese medicines
Modern research has revealed that many Chinese herbs act through one or more pharmacological mechanisms. Many active components have been isolated from herbs used in Chinese medicine and some are used in modern pharmaceutical drugs. They include ephedrine for hypotension (from ephedra (Ephedra sinica Stapf)), artemisinin for malaria (from Chinese wormwood (Artemisia annua L.)), and berberine, an antibacterial component (from Chinese goldthread (Coptis chinensis Franch)). Active components have been defined in many other Chinese herbs, for example anthraquinone glycosides in rhubarb (Rheum officinale Baill), and gingerols in ginger (Zingiber officinale Rosc).
The chemistry of herbal medicines is the foundation of their pharmacology. It is also important for the manufacture and quality assurance of herbal preparations. For example, aconite (Aconitum carmichaeli Debx.) is an 'internal warming, hot and pungent herb' and is used to restore Yang deficiency in heart failure. Its cardiotonic active substance has been isolated and identified as higenamine, a beta adrenergic agonist with an isoquinoline structure related to catecholamines. The active components responsible for analgesic and toxic effects are aconitine, mesaconitine and other diterpene esters, which are largely hydrolysed during processing and boiling. The toxicity of aconite is well understood in traditional Chinese medicine and the herb is only listable at very low concentrations in Australia. Red sage (Salvia miltiorrhiza Bunge) is a herb that is said to 'promote blood circulation and remove blood stasis'. It purportedly dilates the coronary arteries and increases the peripheral circulation so it has been used to treat angina pectoris. However, for most Chinese medicines the active components responsible for their pharmacological activities and clinical applications are not well defined.
The level of clinical evidence to support Chinese medicine does not generally meet the internationally accepted standards of clinical trials of new drugs. Many preclinical and clinical studies carried out in China have been published in the Chinese literature, but the results are not readily available to Western communities.
Quality control from agriculture to fingerprinting
As for pharmaceutical products herbal medicines require professional and government control to ensure their quality, safety and efficacy. The Chinese pharmacopoeia (2000)3 contains monographs and standards of materia medica and patent preparations. Australia relies mainly on imported herbal materials and has not developed a herbal pharmacopoeia.
The quality of a herbal medicine refers to the intrinsic properties of the herb, that is, the amount and range of medicinally useful or active constituents present. The correct identification of a plant with reference to its accepted scientific name(s) is a primary step in the quality assurance process, as a single common name may often refer to different plant species, with potentially dangerous consequences. Other factors influencing the quality of herbal medicines are:
Chinese herbal medicines are usually used as a decoction of a mixture of herbal materials defined in a formula, which therefore contains hundreds of components. The clinical application of Chinese medicines is related to the multiple chemical components and not a single component. A pharmaceutical approach to testing for the content of a single component may therefore not reflect the quality, safety and efficacy of a herbal preparation. Methods of chromatographic fingerprinting, such as high-performance thin layer chromatography and high-performance liquid chromatography, are being developed to define the profiles and variations between herbal medicines.
Safety and regulation of traditional Chinese medicines
The issues associated with the safety and quality of Chinese herbal medicines include toxic herbs, contamination with heavy metals, microbial organisms, and other contaminants, and deliberate combination or adulteration with pharmaceutical drugs. Chinese herbal products in Australia are regulated by the Therapeutic Goods Administration (TGA) and need to meet quality and safety standards (see comment).
The importation and dispensing of raw herbs are not effectively regulated or closely monitored by the TGA. At present, raw herbs can be imported and dispensed legally over the counter without registration with the TGA. These herbs may not meet the standards for herbal products.
Some herbs or minerals are known to be toxic and, when appropriate, need to be used with care under the supervision of highly qualified practitioners. Aconite poisonings have occurred repeatedly overseas and in Australia. Aconite (Aconitum carmichaeli Debx., Aconitum kusnezoffii Reichb.) contains aconitine, a cardiotoxin and neurotoxin causing arrhythmia and ventricular fibrillation. Thornapple (Datura metel L.) and black henbane (Hyoscyamus niger L.) contain hyoscyamine, an antimuscarinic alkaloid. Other toxic herbs requiring special regulation include nux vomica (Strychnos nux-vomica L.) which contains strychnine, Chinese arum (Arisaema erubescens (Wall.) Schott), and tri-leaved pinellia (Pinellia ternata (Thunb.) Breit).
Some species of plants with similar Chinese names differ in their indication and toxicity and cannot be used interchangeably. Guang fang ji (Aristolochia fangchi) and han fang ji (Stephania tetrandra) have similar names and clinical indications in traditional Chinese medicine, but Aristolochia fangchi contains the highly toxic aristolochic acids. Aristolochia fangchi has been found to cause renal failure and urothelial carcinoma. The nephropathy is characterised by extensive interstitial fibrosis leading to a severe atrophy of the proximal tubules.4, 5
Contamination or adulteration
Chinese herbal products have been found to contain heavy metals, such as mercury and arsenic, and non-prescription or even prescription drugs such as paracetamol, indomethacin, chlorpheniramine, aminopyrine, caffeine and hydrocortisone. The unapproved presence of these substances may have originated from mineral components, contamination or adulteration.2Currently quality monitoring relies on TGA post-marketing surveillance. Extra resources would be required to carry out routine surveys of the quality of Chinese herbal products in the Australian market to detect drug contamination or adulteration.
The combination of pharmaceutical drugs and Chinese herbal medicines is a common practice in China and must be considered when patients are using preparations obtained outside Australia. Similarly, patients in Australia may use Chinese medicines together with pharmaceutical drugs without informing their medical practitioners. The potential for drug-herb interactions remains to be investigated.
Regulation of herbal dispensers/pharmacists
Herbal medicines are usually dispensed by the practitioner who prescribes them, even though it is not accepted Australian practice for practitioners to have both prescribing and dispensing functions. It seems reasonable that dispensers should have sufficient training in the theory and properties of herbal medicines, equivalent to that found in pharmacy in Australia and traditional Chinese medicine pharmacy in China, in order for them to dispense herbal medicines safely according to best practice. This would require training in the pharmaceutical aspects of herbal medicines.
Best practice for Chinese medicines in Australia requires understanding both the traditional Chinese medicine system and modern orthodox medicine. There is a need to establish a quality testing system for raw herbs and their preparations and herbal products. This would detect any mislabelling or misidentification and the presence of undeclared components. Herbs with toxicities equivalent to prescription pharmaceutical drugs require a regulatory control system, such as a special schedule to enable registered practitioners to prescribe them under appropriate monitoring. Herbal dispensers should have an adequate qualification for dispensing, which includes knowledge of Chinese medicine and modern pharmaceuticals.
Medical practitioners and pharmacists should have sufficient knowledge of traditional Chinese medicine and herbal medicines to allow them to discuss issues and give advice to patients, and to identify and manage drug-herb interactions. Education programs such as short courses on modern Chinese medicine or exposure to the subject in the undergraduate curriculum may be of benefit to healthcare practitioners.
F U R T H E R R E A D I N G
Quality control methods for medicinal plant materials. Geneva: World Health Organization; 1998.
Bensoussan A, Myers SP. Towards a safer choice: the practice of traditional Chinese medicine in Australia. Sydney: Faculty of Health, University of Western Sydney Macarthur; 1996.
Expert committee on complementary medicines in the health system. Complementary medicines in the Australian health system. Canberra: Commonwealth of Australia; 2003.
Conflict of interest: none declared
Traditional Chinese medicines account for only a small part of the use of complementary medicines in Australia. The problems of quality mentioned in this article are not confined to traditional Chinese medicines. This year's recall of complementary medicines made by Pan Pharmaceuticals shows that problems can arise even when products are manufactured in a modern factory.
The following statements are either true or false (click here for the answers)
1. Traditional Chinese medicines may contain therapeutic and toxic components.
2. The method of preparation of a Chinese medicine may alter its pharmacological effects.