Interactions between modern and Chinese medicinal drugs:
a general review.
American Journal of Chinese Medicine, Spring, 2003, by K.F. Cheng, K.S. Leung, P.C. Leung

Abstract: While the use of health food and over-the-counter drugs for health promotion and adjuvant therapy is becoming increasingly popular, the concern about adverse effects is mounting. The possible adverse effects that may arise from drug interactions between these herbal preparations and standard modern therapy are equally worrying. Herbal toxicity and adverse effects are well documented in classical Chinese medicinal volumes. Interactions between herbal preparations and standard modern therapy are unknown. Extensive work needs to be done before useful guidelines can be established. However, based on available reports and clinical observations, some commonly used herbs and Chinese medicines have already demonstrated the need for special attention when used together with modern therapy. This paper analyzes the important material already available, and would serve as a preliminary checklist for patients who are taking herbal preparations, while at the same time receiving treatment from modern medicine.
Keywords: Chinese Herbs; Adverse Effects.
With the legal recognition of the importance of traditional Chinese medicine in Hong Kong, its practice is becoming more and more diverse. Some hospitals have already started practicing Chinese herbal medication. The potential of the integration of Chinese and modern medicine in future medical practice must, therefore, not be underestimated. Hence,
the unavoidable interaction between Chinese and modern medicine needs to be understood. Will such therapies enhance or worsen the treatment outcome, or even be harmful? This is the question awaiting to be answered by those who have been inspired. On the other hand, traditional Chinese medicine has increasingly been practiced in the Western society. It is known that such usage has already caused serious complications in anesthetics in a number of occasions (The American Society of Anesthesiologists, 2001). For this reason, the interactions between Chinese medicine and anesthetics should not be ignored.
The Relationship Between Dosage and Toxicity
It has been found that many Chinese (or herbal) medicine or modern drug therapies are only beneficial to a patient if they are given at certain dosages. When they are used at other dosages instead, they turn out to be noxious.
The famous Chinese doctor Zhang Zhi He of the Yuan Dynasty (about 1300 AD) has once wrote in Enlightening Case Reports (Ru Men Shi Qing [TEXT NOT REPRODUCIBLE IN ASCII]) (Zhang, 1300) "Toxicity is a property of all drugs--not just that poisons are toxic. One must not forget herbs such as Liquorice (Radix Glycyrrhizae) and Radix Sophorae Flavescentis can be toxic too. Undesirable outcomes follow any type of overdosages." There is, in fact, no such thing as a non-toxic drug. Both toxic and curative potentials are properties of all drugs. The key to successful treatment is to select the right drug, the right dosage and the right administration. For every drug, there is a direct relationship between its dosage and the severity of its toxicity or side effects.

The interaction of Chinese and modern medicine may be synergistic; it may also be antagonistic, or even be noxious. Simultaneous practice of Chinese and modern medicine may complicate the control of dosages of any patient's long-term medications. It has already been reported that the traditional Chinese medicine for diabetic control, if used with insulin injection or oral antidiabetics, may cause hypoglycemia (The American Society of Anesthesiologists, 2001).
The interactions between Chinese herbs and modern drugs are a common issue, yet reports on them are very rare. According to research on 1000 elderly patients admitted through the accident and emergency department, 538 of them have used over 1087 types of drugs, and 30 of them have been affected by the side-effects of these drugs (Doucet et al., 1996). In fact, either within the hospital or outside, when patients self-prescribe, multi-drug therapies are commonly practiced. Prescribed drugs, proprietary drugs, vitamins, herbal medicines, food, etc. may all interact and affect the treatment outcome.
Interaction Between Chinese and Modern Medicine
Some drug interactions have been investigated by in vitro and in vivo experiments, but results obtained have been inconsistent. St. John's wort, an herb commonly used in Western societies, was shown to suppress monoamine oxides in vitro, but such observations were absent in in vivo studies. Hence, there is insufficient evidence of the antioxidant activity of St. John's wort causing hypertensive crisis. However, recently, it was reported in Switzerland that St. John's wort may interact with other drugs, e.g. the simultaneous administration of St. John's wort with digoxin, amitriptyline or theophylline may reduce the effectiveness of the three drugs. When two patients with heart transplantation were given St. John's wort while receiving their cyclosporin treatment, they both had severe rejections within three weeks. When the patients discontinued the herbal drug, the cyclosporin blood concentrations increased (Ruschitzka et al., 2000).
Some medications from natural products possess monoamine oxides inhibitory activity, e.g. Cornu cervi pentotrichum, Fructus crataegi, Radix polygoni multiflori, etc. (Yang, 1996). If tyramine-containing food, e.g. cheese, pickled fish, chocolate, yeast, liver, beer, red wine or yoghurt is taken when the above natural products are used, hypertension, palpitation, headache, nausea, etc. may result (Wang et al., 2000).
Potential Integration of Chinese and Modern Medicine
Using Chinese herbal medicine as food supplements or health food is very popular. A survey done in America reported that among adults taking regular prescriptions, 18% also took at least one extra type of herbal medicine or high-dosages of vitamins, and 61% of them did not notify their doctor (Eisenberg et al., 1998). In Britain, a survey of 515 individuals receiving herb medications showed that 26% had to seek for medical advice due to discomfort caused by interactions between the herbal and prescribed medication (Barnes et al., 1998). Many patients would not ask for medical help even when they experienced serious drug complications because they were afraid of disapproval. For this reason, as a doctor, one should use a friendly holistic approach to make it easy for patients to report about the usage of non-prescribed drugs, such that an accurate tailor-made prescription could be made. Moreover, such drug histories could be useful as references when adverse effects might appear in future.
Appropriate integration of Chinese and modern medicine may have synergistic effects such that treatment outcome is enhanced and side-effects are suppressed. For example, in the case of tonsillitis, co-administration of Radix Isatidis (Banlangen) with Trimethoprin (TMP) significantly enhances the immune system, the outcome may be much better than administration of either drug alone. Flos Lonicerae (Jinyinhua) increases the effectiveness of penicillin on drug-resistant Staphylococcus aureus, the synergistic interactions of Rhizoma Coptidis (Huanglian), Cortex Phellodendri (Huangbo) and tetracycline, acheomycin, aspirin, TMP often initiated a better outcome in the treatment of diarrhoea and malaria. The co-administration of Liquorice and Streptomycin reduced the toxicity of the latter on the auditory nerve (Zhu, 1991).
Conversely, disastrous outcomes may follow inappropriate usage of Chinese and modern medicine: antagonistic interactions resulting in reduced or loss of curative potential, enhanced side-effects, or even death. For example, co-administration of digoxin and Liu Shen Pill (Liushenwan) led to repeated ventricular extrasystoles (Zhu, 1991); mixing Cinnabaris (Zhusha) containing Chinese Medicine with halogen compounds can be extremely toxic (Zhang, 1997). Hemophiliacs, patients on anticlotting treatment and those who have been scheduled for operations should refrain from taking ginkgo, danshen, danggui, garlic and papaya. The co-administration of herbal ephedrine and monoamine oxidase inhibitors increases the risks of hypertensive crisis and cerebral vascular accidents.
Some herbal medicine, even when used alone, should not be overdosed. Aloe vera is one of these, commonly used but not suitable for all. Children and those with ill health, if overdosed on Aloe vera, present with hypersensitive reaction--erythema, psoriasis, and even nausea and diarrhorrea-like symptoms. In particular, pregnant women and those menstruating should not use Aloe vera since it may increase the vascularity of the female organs, stimulate uterine mobilities, and cause epigastric pain and severe bleeding. Patients suffering from haemorrhoids and epistaxis could suffer from enhanced symptoms by taking Aloe vera (Tan, 2001).

The interactions mentioned above make up merely a small percentage of possible drug interactions. A lot of work is still awaiting to be done in a systematic search for the interactions between Chinese and modern drugs. Hence, when practicing the integration of Chinese and modern medicine, one should watch out for the reactions of patients to the drugs and integrate this information to the overall planning in the therapy. While trying to maximize treatment efficiency by including alternative medicine, it is of utmost importance that patient safety should come before all else.