Three Points of Convergence Between Modern Pharmacology and Traditional Chinese Medicine

Abstract

Modern pharmacology and traditional Chinese materia medica belong to two distinct theoretical systems: the former is founded on experimental science, whereas the latter centres on holism and treatment based on syndrome differentiation. A careful comparison, however, reveals several striking parallels in the way each understands the regularities of drug action. This paper examines three such correspondences - the excitatory and inhibitory actions of drugs versus the therapeutic principle of "reduce the excessive, supplement the deficient"; the selectivity of drug action versus the theory of channel (meridian) tropism; and the preventive and therapeutic effects of drugs versus treatment based on syndrome differentiation and disease differentiation. These similarities suggest that Chinese and Western medicine are not diametrically opposed but can complement and corroborate one another, and that fostering dialogue between the two systems may help deepen our understanding of drug action and promote more precise, safer and more effective clinical drug use.

Keywords: modern pharmacology; traditional Chinese medicine; drug selectivity; channel tropism; syndrome differentiation

Introduction

Modern pharmacology is the discipline that studies the interaction between drugs and the organism and the mechanisms underlying their effects, using modern scientific methods to elucidate the laws of pharmacodynamics and pharmacokinetics. Traditional Chinese materia medica, guided by the theoretical framework of traditional Chinese medicine (TCM), studies the nature and flavour of drugs, their channel tropism, therapeutic actions and indications, and the principles of compatibility. The two belong to different theoretical systems: the former is founded on experimental science, whereas the latter centres on holism and treatment based on syndrome differentiation.

A close comparison of their theoretical frameworks, however, reveals several striking similarities in the way they understand the regularities of drug action. This paper explores three correspondences between the two systems: the excitatory and inhibitory actions of drugs correspond to the therapeutic principle of "reduce the excessive, supplement the deficient"; the selectivity of drug action corresponds to the theory of channel (meridian) tropism; and the preventive and therapeutic effects of drugs correspond to treatment based on syndrome differentiation and treatment based on disease differentiation.

1. The Excitatory and Inhibitory Actions of Drugs and the TCM Idea of "Reduce the Excessive, Supplement the Deficient"

Modern pharmacology holds that excitation and inhibition are the two fundamental actions of drugs. Excitation refers to a drug raising the pre-existing functional level of an organ, as when adrenaline (epinephrine) accelerates the heart rate and raises blood pressure, or furosemide increases urine output; inhibition refers to a drug lowering the pre-existing functional level of an organ, as when omeprazole reduces gastric acid secretion or diazepam depresses central nervous system excitability. These two concepts are the foundation of pharmacology and an important basis for the rational use of drugs in clinical practice.

The idea of "reduce the excessive, supplement the deficient" originates in Laozi's Dao De Jing and in the Huangdi Neijing (The Yellow Emperor's Classic of Internal Medicine), a TCM classic, and is one of the fundamental principles of TCM treatment. Its core is that disease arises from an imbalance of yin and yang and a dysregulation of qi and blood, and that the aim of treatment is to "reduce what is excessive" so as to eliminate hyperactive pathological factors, and to "supplement what is deficient" so as to restore the weakened vital qi (zheng qi).

For example, for a patient with hyperactivity of liver yang, pacifying the liver and subduing the yang constitutes "reducing the excessive"; for a patient with a deficiency of qi and blood, replenishing qi and nourishing blood constitutes "supplementing the deficient". This principle embodies the holistic, regulatory thinking of TCM - restoring the body's dynamic equilibrium in order to treat disease.

The excitatory and inhibitory actions in modern pharmacology are highly similar in logical structure to the TCM principle of "reduce the excessive, supplement the deficient". Specifically:

First, the excitatory action corresponds to "supplementing the deficient". When the function of an organ is depressed, a drug with an excitatory action can raise its functional level, which accords with the TCM idea of "supplement what is deficient". For example, adrenaline used to rescue a patient from anaphylactic shock by raising blood pressure is analogous to the TCM use of warming yang and augmenting qi to rescue a critical collapse of yang; the TCM yang-supporting herbs Aconitum (fuzi), Cinnamon bark (rougui) and Ginseng (renshen) do indeed have cardiotonic and blood-pressure-raising effects.

Second, the inhibitory action corresponds to "reducing the excessive". When the function of an organ is hyperactive, a drug with an inhibitory action can lower its functional level, which accords with the TCM idea of "drain what is excessive". For example, omeprazole suppresses gastric acid secretion to treat peptic ulcer, which is analogous to the TCM use of clearing heat and draining fire to eliminate the pathological state of stomach-fire hyperactivity.

Third, both embody a therapeutic ideal of "restoring balance". Pharmacology restores the normal functional level of the body through excitation or inhibition, while TCM restores the balance of yin and yang through "reduce the excessive, supplement the deficient". Although their theoretical languages differ, their core aim is the same - to bring an organism that has deviated from its normal state back into balance.

2. The Selectivity of Drug Action and the Channel (Meridian) Tropism Theory of Chinese Materia Medica

Selectivity of drug action means that, at therapeutic doses, most drugs act particularly conspicuously on a certain tissue or organ while acting inconspicuously, or not at all, on other tissues or organs. It should be emphasised that the therapeutic dose matters: if the dose is too small or too large, selectivity may not exist at all.

Drug selectivity determines the scope of a drug's action within the organism; it is the basis of drug classification and a principal basis for drug selection in clinical practice. Drugs with high selectivity act over a narrow range, are highly targeted, and produce fewer adverse reactions; drugs with low selectivity act over a broad range, are less targeted, and produce more adverse reactions. Selectivity is relative: as the dose increases, the scope of action broadens and selectivity decreases accordingly.

Chinese materia medica has a similar concept, namely the channel (meridian) tropism of a drug, which holds that certain drugs have a specific action on a particular channel or channels. This theory shares an inherent consistency with the modern pharmacological notion of the selectivity of drug action.

The channel-tropism theory is one of the important theories of Chinese materia medica. TCM holds that certain drugs have a specific affinity and action tendency toward a particular channel (viscera and meridians). For example, Platycodon (jiegeng) enters the lung channel and excels at treating lung disorders, while Bupleurum (chaihu) enters the liver and gallbladder channels and excels at soothing the liver and relieving depression. The channel-tropism theory guides clinical drug selection so that a drug can act precisely on the diseased viscera and channels, thereby enhancing efficacy and reducing adverse reactions.

The selectivity of drug action in modern pharmacology and the channel-tropism theory are essentially akin:

First, both stress the "directed action" of a drug. Pharmacology holds that a drug acts selectively on specific tissues or organs; the channel-tropism theory holds that a drug tends toward specific channels and viscera. Although they are expressed differently - the former based on molecular targets such as receptors and enzymes, the latter on the theory of channels and viscera - both recognise that a drug is not distributed uniformly throughout the body but acts preferentially on particular sites.

Second, both the selectivity and the channel-tropism theories guide precise clinical drug use. Pharmacology classifies drugs and guides their selection according to selectivity; the channel-tropism theory guides syndrome-based drug selection according to channel tropism. Both aim at "delivering the drug to the site of disease" and enhancing therapeutic targeting.

Third, both recognise the relativity of action. Pharmacology notes that a drug's selectivity decreases as the dose increases; the channel-tropism theory likewise acknowledges the phenomenon of "one drug, multiple channels" - most drugs do not enter a single channel but several, and their tropism can be altered by compatibility (formal combination of herbs). Both reflect a profound understanding of the complexity of drug action.

3. Preventive and Therapeutic Effects of Drugs and TCM's Treatment Based on Syndrome Differentiation and Disease Differentiation

Modern pharmacology divides the preventive and therapeutic effects of drugs into three types: preventive action, causal treatment (treating the root) and symptomatic treatment (treating the branch). The preventive action refers to using a drug before a disease occurs to prevent its occurrence, as with vaccination to prevent infectious diseases or antiplatelet drugs to prevent thrombosis; causal treatment refers to treating the aetiology of a disease so as to eliminate the pathogenic factor, as with antibiotics to kill pathogenic microorganisms or insulin to treat diabetes; symptomatic treatment refers to treating the symptoms of a disease to relieve the patient's suffering, as with antipyretics to lower body temperature or analgesics to relieve pain.

Traditional Chinese medicine likewise contains the idea of preventing disease, emphasising that "when the vital qi (zheng qi) resides within, pathogenic factors cannot invade", and advocating "treating disease before it arises (preventive treatment)", that is, intervening before a disease occurs or worsens. At the same time, in treating disease TCM follows two great principles: treatment based on syndrome differentiation and treatment based on disease differentiation. Treatment based on syndrome differentiation selects the corresponding therapeutic method according to the patient's specific syndrome (such as cold or heat, deficiency or excess, exterior or interior, yin or yang), embodying individualised treatment; treatment based on disease differentiation selects the corresponding therapeutic method according to the disease name and its pathological features, embodying recognition of the commonalities of a disease.

The classification of preventive and therapeutic effects in modern pharmacology is highly similar in logical structure to TCM's treatment based on syndrome differentiation and disease differentiation. Specifically:

First, the preventive action corresponds to TCM's idea of "treating disease before it arises". Pharmacology stresses using drugs before a disease occurs, such as statins to prevent cardiovascular disease or anti-osteoporosis drugs to prevent fracture; TCM stresses that "the superior physician treats disease before it arises", advocating the prevention of disease by regulating constitution and strengthening the vital qi. Both embody the medical ideal of "prevention first" - reducing the risk of disease through early intervention.

Second, causal treatment corresponds to TCM's treatment based on disease differentiation. Causal treatment in pharmacology targets the aetiology, such as antiviral drugs for viral infection or antihypertensive drugs for hypertension; TCM's treatment based on disease differentiation selects the method according to the disease name and pathology, such as using nourishing yin and clearing heat for "xiao-ke (wasting-and-thirsting) disease" (analogous to diabetes) or activating blood and resolving stasis for "chest impingement (xiong-bi)" (analogous to coronary heart disease). Both stress treating the essence of the disease, that is, "treating the root".

Third, symptomatic treatment corresponds to TCM's treatment based on syndrome differentiation. Symptomatic treatment in pharmacology targets symptoms, such as antitussives to relieve cough or antidiarrhoeals to relieve diarrhoea; TCM's treatment based on syndrome differentiation selects the method according to the specific syndrome, such as using acrid-warm exterior-releasing methods for a "wind-cold common cold" or acrid-cool exterior-releasing methods for a "wind-heat common cold". Both stress relieving symptoms, that is, "treating the branch".

Fourth, both embody the ideal of "treating root and branch together". In actual clinical practice, Western medicine usually combines causal treatment with symptomatic treatment, and TCM likewise combines syndrome-based with disease-based treatment, so that both the branch and the root can be addressed. It should be noted that treating the root is medicine's ultimate pursuit; yet given the present level of medical science, neither TCM nor Western medicine can yet "treat the root" for many diseases, and being able to "treat the branch" is already no small achievement.

Conclusion

Although modern pharmacology and traditional Chinese materia medica belong to different bodies of knowledge, comparison shows that there is a logical isomorphism between the excitatory and inhibitory actions of drugs and "reduce the excessive, supplement the deficient", an essential congruence between the selectivity of drug action and the channel-tropism theory, and a shared ideal between the preventive and therapeutic effects of drugs and treatment based on syndrome and disease differentiation.

These three similarities suggest that Chinese and Western medicine are not diametrically opposed in their understanding of the regularities of drug action but can complement and corroborate one another from different perspectives. In the development of contemporary medicine, promoting dialogue and integration between the two theoretical systems helps to deepen the understanding of the regularities of drug action and to advance more precise, safer and more effective clinical drug use.