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.
Introduction
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).
Conclusion
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.