ABSTRACT
Oriental medicines, including Chinese medicine (CM), are a complex and holistic system of medical practice with its own philosophy, diagnosis, treatment systems, and pharmacology. They consider the human body in relation to its own natural, physical, and social environment. The practice of CM involves physical therapy (nonmedication) using acupuncture, moxibustion, and related disciplines such as
tuina
massage and
qi gong,
and chemical therapy using Chinese medicinal materials (CMM) of animal, mineral, and plant origin in the form of decoctions of combined CMM or related proprietary products. As most of them are from plants, medical books on CMM, throughout the ages, have conveniently referred to them as
ben cao
(herbalism). Herbal medicines are mixtures of more than one active
ingredient. The multitude of pharmacologically active compounds obviously increases the likelihood of interactions taking place. Hence, the likelihood of herb-drug interactions is theoretically higher than drug-drug interactions, if only because synthetic drugs usually contain single chemical entities. Case reports and clinical studies have highlighted the existence of a number of clinically important interactions, although cause-and-effect relationships have not always been established. Herbs and drugs may interact either pharmacokinetically or pharmacodynamically. Through induction of cytochrome P450 enzymes and/or P-glycoprotein, some herbal products (e.g.,
St John’s wort
) have been shown to lower the plasma concentration (and/or the pharmacological effect) of a number of conventional drugs, including
cyclosporine
,
indinavir
,
irinotecan
,
nevirapine
,
oral contraceptives
, and
digoxin
. The majority of such interactions involve medicines that require regular monitoring of blood levels. To date there is less evidence relating to the pharmacodynamic interaction. However, for many of the interactions discussed here, the understanding of the mechanisms involved is incomplete. Taking herbal agents may represent a potential risk to patients under conventional pharmacotherapy.
