Chinese Herbal Medicine

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Chinese Herbal Medicine (CHM) is the central pillar of Traditional Chinese Medicine (TCM) and East Asian Medicine (EAM) writ large. Documented evidence of both herbal medical theory and use of medicinal substances appears in literature and archeological evidence dating back more than 3000 years. Throughout this period, CHM has been extensively used in Asia as a primary form of treatment [1,2]. In China, CHM is sought by patients at an estimated 1.28 billion clinical visits per year. Of all TCM available in China (including acupuncture, massage, and Qigong therapy), CHM accounts for 90% of traditional medicine use[3]. The use of Chinese herbs and herbal medicine have recently spread to Western countries and become part of a multibillion-dollar herbal industry [4].

The practice of CHM depends upon the development and maintenance of an encyclopedia of medicinal substances, an herbal pharmacopoeia, in which medicinal substances are described and classified. The current standard pharmacopoeia in China contains some 10,000 medicinal substances [5]. At present, there are a variety of pharmacopeias available; in the United States the standard pharmacopoeia includes over 400 substances [6]. Entries for each substance include the assigned qualities and therapeutic functions for that substance, physical characteristics with information on possible substitutions, as well as particular pairings of herbs which when combined, are described as having particular synergistic therapeutic effects. Individual medicinal substances are dried and processed in numerous ways that alter the traditional functions and chemical components of each substance, for example, substances may be cooked for hours, fried in vinegar, or calcined (charred). On average, an herbalist will regularly employ some 200–400 substances in his or her clinical practice. CHM is typically administered in formulas based on a combination of classical or modern prescriptions that include from 6 to 14 medicinal substances, i.e., vegetable, mineral and animal materials described in the Chinese herb pharmacopoeia.

Herbal formulas are customized to address each patient's condition, and while biomedical diagnoses and lab results are included in a patientís intake, the formula prescribed by the herbalist focuses on the TCM diagnosis. For example, a patient presenting signs and symptoms of a peptic ulcer with confirming Upper GI endoscopy and a positive HpSA lab suggests an infection by H. pylori. While this patient has a single biomedical diagnosis, he or she could be given a number of TCM diagnoses: Cold in the Stomach, Heat in the Stomach, Deficient Middle Warmer with Rebellious Stomach Qi, Blood Stasis in the Stomach/Spleen, Liver Qi Invading the Stomach, Stomach Yin Deficiency, Spleen and Stomach Qi Deficiency with Food Stagnation. Each diagnosis implies treatment strategies specific to its TCM diagnosis and calls for herbs and formula with specific functions. Each of these diagnoses could be used to treat a peptic ulcer.

For further information on TCM diagnoses consult A Practical Dictionary of Chinese Medicine by Nigel Wiseman, Ye Feng.

Scientific Evaluation of Chinese Herbal Medicine

Much research has been devoted to exploring the biomedical and pharmaceutical potential of Chinese herbs. The majority of this work has been laboratory-centered and has focused on the isolation of functional chemical substances, identification of chemical compounds in single herbs, and characterizing their pharmacological properties. A number of substances from the Chinese herbal pharmacopoeia have been analyzed using standard pharmacological chemical and bioassay procedures, i.e., using tissues, isolated organs, model laboratory animals, and in some cases, humans [7,8,9,10,11]. Two examples of drugs derived from Chinese herbs are ephedrine from Ephedra sinica/Ma Huang [10]and Artemisinin/Qing Hao, an antimalarial drug from Artemisia apiacea [12]. Pharmacokinetic studies with Chinese herbs have also begun to characterize how chemical constituents are utilized and metabolized once introduced into animals and humans [13].

Scientific evaluation of herbal substances is used within the Traditional Chinese Medicine profession itself, particularly by herb manufacturers and distributors, both in profiling the properties of a substance as well as testing for biological and chemical adulteration. Concerns regarding the selection of proper varieties of plants and substances as well as peak growing, harvesting and processing of substances have driven the use of thin-layer chromatography (TLC) to produce profiles of batches of medicinal substances throughout the manufacturing and distribution process. TLC is used by many herb companies importing to the US including Sun Ten Laboratories, Inc. and Kaiser Pharmaceutical Co., Ltd.

Challenges of Scientifically Evaluating
Chinese Herbal Medicine

Limitations of Scientific Research on Chinese Herbal Medicine (CHM)

Research to date on the efficacy and safety of CHM is limited for a variety of reasons. First, demonstrating pharmacological activity on isolated tissues, organs or laboratory animals does not necessarily translate into clinical effectiveness in humans. Second, most pharmacological studies in the West have not relied on herbs prepared and administered using traditional methods. Rather, they have emphasized the effects of isolated active ingredients of single herbs. These extraction methods may not reflect the full spectrum of effects of traditionally prepared herbs. Moreover, use of single herbs does not reflect multi-herb traditional formulas and ignores Chinese theories of herb interactions. There is little doubt that under many conditions, components of herbal mixtures interact and influence each other beneficially [1,14]. The language of traditional formulas reflects the intended interactive and coordinated nature of elements within a mixture. Texts as far back as the 2nd century refer to individual substances in formula as being assigned functional roles, then referred to as 'chief,' 'deputy,' 'assistant,' and 'envoy'; their understanding was that it took multiple roles and functions to accomplish the treatment aims sought, akin to running a government or fighting a war [6,14]. Recent research has substantiated the theory that elements of traditional Chinese formulas interact in the body in complex ways, sometimes synergistically with one element enhancing the effect of others and sometimes with one element preventing negative or toxic effects of others [15]. Finally, even when traditionally prepared herbs or mixed formulas have been studied, they are not always evaluated within the full context of Traditional Chinese Medicine (TCM). For example, recent studies in Europe and the US evaluating the efficacy of mixed Chinese herbal formulas for biomedical diseases have primarily used fixed formulas [16,17,18], and have not taken into account that for any given biomedical disease (e.g. diabetes, hypertension), there may be many different East Asian Medicine differential diagnoses.

One RCT Reviewed: Chinese Herbal Medicine for Irritable Bowel Syndrome

One trial conducted that aimed to adhere to traditional Chinese diagnostic and treatment strategies while using a strict double-blind methodological protocol warrants particular attention. Bensoussan and colleagues [19] in Australia randomly assigned 116 patients with irritable bowel syndrome to one of three treatment arms: placebo herbs, a standardized Chinese herbal formulation, and an individualized herbal mixture prescribed by a traditional Chinese herbalist. The standard formula contained twenty ingredients and the tailored prescriptions consisted of herbs chosen from a total of eighty-one herbs to match the unique pattern of disharmony and symptoms of each patient. Placebo substances were designed to taste, smell, and look like an herbal formula. The treating herbalists who made the diagnoses and prescriptions were blinded with regard to the arms subject were randomized to. Compared to the placebo group, patients in the active treatments had significant improvements on all outcome measures. Standardized and individualized formulations were equally effective at the end of the 16-week treatment phase, however, at a subsequent 14-week follow-up, only those patients with individualized herbs maintained improvements.

Adverse Effects Associated with Chinese Herbal Medicine and Interactions with Biomedical Pharmaceuticals

Chinese Herbal Medicine (CHM) has been thought to have much lower risks when compared with its biomedically-based pharmaceutical counterparts. A recent report from China indicated that CHM was responsible for 34 of 378 (8.99%) reported cases with drug adverse reactions in a six month period. Among these 34 cases, 18 cases (4.76%) were associated with herbal injections, which are only available in hospitals in China, and 16 cases (4.23%) with oral administration [20].

The following factors have been reported with the occurrence of adverse reactions with Chinese Herbal Medicine:

Misidentification. Misidentification of herbal species can lead to toxic reactions. In the cases of "Chinese herb nephropathy," Guang Fang Ji /Aristolochiae Fangchi, a species containing Aristolochic Acid, a known nephrotoxin substance, was mistakenly substituted for Han Fang Ji/Stephaniae Tetrandrae, the herb originally prescribed by the medical doctors . See FDA's Center for Food Safety & Applied Nutrition, "Dietary Supplements: Aristolochic Acid."
Adulteration and contamination. Due to inadequate quality control process and lack of good manufacturing practice (GMP) standards, some Chinese herbal medicine products, most notably "patent medicines," were found to contain heavy metal substances (lead, arsenic and mercury [21,22]. Further, undeclared pharmaceuticals were identified in herbal products marked for the US market. For example, PC-SPES and SPES, two herbal products for "prostate health," were found containing warfarin and alprazolam, which led to a warning issued by the FDA.
Drug-herb interactions. Information on drug-herb interactions in CHM is limited. Several case reports have suggested that Dang Gui or Dong Quia (Angelicae Sinensis), a Chinese herb with a property called "Invigorate blood" in CHM system, is associated with an significantly increased prothrombin time and international normalized ratio (INR) in patients who are on warfarin therapy [23,24,25]. However, an observational survey conducted at a warfarin clinic in Hong Kong found that of 107 patients interviewed, 28 (26%) claimed to have taken herbal medicines during the week prior to the clinic visit and the users of herbal medicine had lower INR values than non-users (p=0.019). None of the patients in this study showed any evidence of thromboembolism or bleeding on the day of the clinic visit [26].
Misuse. On Febuary 11, 2004, the FDA issued a final ruling prohibiting the sale of dietary supplements containing ephedrine alkaloids. Ephedra, known as Ma Huang in Chinese, has been used primarily for colds and asthmatic condition in CHM for thousands of years. Clinically, Ma Huang is only used in predefined clinical conditions, small quantity, short term, and combined with other herbs together to minimize its potential side effects. A patient who uses Ma Huang is required to be monitored by a practitioner trained in Chinese medicine. Using Ma Huang as a weight loss dietary supplement substantially deviates from the context of the original diagnostic framework and practice of Traditional Chinese Medicine (TCM) and as such is reflected in the 2004 FDA ruling on Ephedra use.

The FDA ruling (see comment 44) states:

"Several Ephedra species (including those known as Ma Huang) have a long history of use in traditional Asian medicine. These products are beyond the scope of this rule because they are not marked as dietary supplements. . . This final rule does not affect the use of ephedra preparations in traditional Asian medicine, although we considered the comments' [sic] views and information on the use of Ephedra in traditional Asian medicine in the context of their possible relevance to the risks of dietary supplements containing ephedrine alkaloids. This rule applies only to products regulated as dietary supplements."

CHM has been used by millions of people over thousands of years. By considering billions of people who are utilizing Chinese herbal medicine for their health care needs, the reported adverse reactions caused by Chinese herbs are still relatively small. To ensure patient safety, research on adverse reactions caused by CHM are urgently required to further deepen our understandings of these medicinal substances.