The Characters and Functions of Traditional Chinese Drugs
Each
drug has its own specific characters. In traditional Chinese medicine, the different
characters of drugs are employed to treat diseases, rectify the hyperactivity
or hypoactivity of yin or yang, and help the body restore its normal physiological
functions, consequently curing the diseases and restoring health. The various
characters and functions of these drugs concerning medical treatment include drugs'
properties, flavors, actions of lifting, lowering, floating and sinking, channel
tropism, toxicity, etc. The theory of characters and functions of traditional
Chinese drug is based on the theories of yin and yang, viscera, channels and collaterals,
and treatment principles of traditional Chinese medicine, and has been developed
and summed up throughout a long history of medical practice. This theory provides
the basis for drug analysis and application.
1. Properties and Flavors of Traditional
Chinese Drugs
Properties and flavors are also known as four properties and
five flavors. Every drug has its property and flavor. "Property" refers
to the cold, hot, warm or cool nature of a drug. These properties of drugs are
so sorted out according to the different actions of the drugs on the human body
and their therapeutic effects. For example, drugs that cure heat syndrome (yang
syndrome) have a cold or cool property, whereas drugs that cure cold syndrome
(yin syndrome) have hot or warm property.
Drugs of cold and cool natures and
drugs of warm and hot natures are of opposite properties. A cold-natured drug
is different from a cool-natured one only in degree, and so is a warm-natured
drug from a hot-natured drug. Most of the cool- or cold -natured drugs have the
effects of clearing heat purging fire, removing toxic substances, and nourishing
yin, and are used to cure heat syndromes. On the contrary, drugs of warm or hot
nature usually have the effects of dispersing cold, warming up the interior, supporting
yang, and treating collapse, and are therefore used to treat cold syndromes. In
addition to the four properties mentioned above, there is the fifth, the neutral
or mild one. When a drug is neither hot nor cold in nature, it is said to be neutral.
It can be used for either hot or cold syndromes. Yet, drugs of neutral nature
usually tend to be either slightly hot or slightly cold. That is why drugs are
generally said to be of four properties only.
"Flavors" refers to
the tastes of drugs, i. e. pungent, sweet, sour, bitter, salty, tasteless and
astringent. Since sweet and tasteless usually coexist, and since sour and astringent
drugs have the same effects, pungent, sweet, sour, bitter and salty tastes are
the cardinal flavors and are habitually known as five flavors. Drugs of different
flavors and different compositions show different pharmacological and therapeutic
actions, while drugs of the same taste usually have similarities in effect and
even in composition. The flavors don't necessarily refer to the real tastes of
the drugs. Sometimes they are sorted out according to drugs' actions other than
tastes. Therefore, the flavors of some drugs described in books on materia medica
are often different from their true tastes. Various flavors have different effects.
They are explained separately as follows:
Pungent flavor: Drugs that are pungent
in flavor have the effects of dispersing exopathogens from superficies of the
body and promoting the circulation of the vital energy and blood. Pungent drugs
are usually used for the treatment of superficial and mild illnesses due to affection
by exopathogens, stagnation of vital energy, blood stasis, etc.
Sweet flavor:
Drugs of sweet flavor have the effects of nourishing, replenishing, tonifying,
or enriching the different parts or organs of the body, normalizing the function
of the stomach and spleen, harmonizing the properties of different drugs, relieving
spasm and pain, etc. Drugs of sweet flavor are usually effective in treating syndromes
of deficiency type, dry cough, constipation due to dry intestine, incoordination
between the spleen and the stomach, various pains, etc. Besides, some of the sweet
drugs have the effects of detoxication.
Sour flavor: Drugs of sour flavor have
the effects of inducing astringency and arresting discharge. Sour drugs are often
used to treat sweating due to debility, chronic cough, chronic diarrhea, emission,
spermatorrhea, enuresis, frequent micturition, chronic leukorrhagia, metrorrhagia
or metrostaxis, etc.
Bitter flavor: Drugs of bitter flavor have the effects
of clearing heat, purging fire, sending down the adverse flow of qi to treat cough
and vomiting, relaxing the bowels, eliminating dampness, etc. Such drugs are mostly
used for syndromes of pathogenic fire, cough with dyspnea, vomiting, constipation
due to heat of excess type, damp-heat syndrome, or cold-damp syndrome and other
syndromes.
Salty flavor: Drugs of this taste have the effects of relieving
constipation by purgation, and softening and resolving hard mass. Salty drugs
are mostly used in treating dry stool and constipation, scrofula, goiter, mass
in the abdomen, and other problems.
Tasteless flavor: Drugs of this flavor
have the effects of excreting dampness and inducing diuresis, and are commonly
used for edema, dysuria and others.
Astringent flavor: Drugs of this flavor
have similar actions as those of sour flavor.
Drugs of the same flavor generally
have similar actions, and drugs of different tastes have quite different actions.
Yet some drugs are the same in property but different in flavor, or the same in
flavor but different in property, and, therefore, their effects are not all the
same. Both coptis root and dried rehmannia root, for instance, have the same cold
property, yet coptis root is bitter in flavor while dried rebmannia root sweet.
The former has the effects of clearing heat and drying dampness and is used for
damp-heat syndrome, while the latter has the effects of clearing heat and nourishing
yin and is used for the condition of consumption of yin due to febrile diseases.
Another example is the use of ephedra and peppermint, both of which have a pungent
flavor. However, the property of ephedra is warm, whereas the property of peppermint
is cool. The former has the effects of dispersing wind-cold pathogens and is used
to treat exterior wind-cold syndrome, while the latter has the effects of dispersing
pathogenic wind-heat and is used to treat exterior wind-heat syndrome. Therefore,
the property and flavor of a drug should not be treated separately but should
be taken into consideration as an integrated whole. Only in this way can drugs
be understood and used correctly.
2. Actions of Lifting, Lowering, Floating
and Sinking
Actions of lifting, lowering, floating and sinking refer to the
upward, downward, outward or inward directions in which drugs tend to act on the
body. Lifting means going up or sending up while lowering means just the opposite.
Floating means going outward or sending to the surface, whereas sinking means
going inside or purging away. Lifting and floating drugs have upward and outward
actions and are used for elevating yang, relieving exterior syndromes by means
of diaphoresis, dispelling superficial wind and cold, inducing vomiting, causing
resuscitation, etc. Lowering and sinking drugs have downward and inward actions
and are used for clearing heat, purgation, promoting micturition, removing dampness,
checking the exuberance of yang, sending down an adverse flow of qi to stop vomiting,
relieving cough and asthma, improving digestion to remove stagnated food, tranquilizing
the mind with heavy properties, etc. As the locations of diseases are different
with some in the upper part of the body and some in the lower, some in the interior
and some in the exterior, and as the tendencies of diseases are divided into upward
(as with vomiting), downward (e. g. diarrhea, metrorrhagia, metrostaxis and proctoptosis),
outward (e. g. spontaneous or night sweating) and inward (e. g. internal transmission
of exterior syndrome), the lifting, lowering, floating and sinking actions of
drugs are used in correspondence with the locations of diseases but in opposition
to the tendencies of diseases. Generally speaking, for the diseases located in
the upper part or the exterior, it is appropriate to use lifting and floating
drugs instead of the lowering and sinking. For example, for the exterior syndromes,
lifting and floating drugs should be chosen. On the contrary, for the diseases
located in the lower part or the interior, such as dry stool or constipation,
it is proper to use lowering and sinking drugs, not the opposite. For the diseases
of which the manifestations tend upward, drugs of lowering actions should be given
rather than that of lifting, just as in the treatment of headache and vertigo
due to hyperactivity of the liver-yang, drugs of lowering and sinking actions
should be used to calm the liver and suppress hyperactivity of the liver-yang.
On the contrary, for the diseases of which the manifestations tend downward, it
is suitable to use lifting drugs instead of lowering drugs. For example, in the
treatment of chronic diarrhea and proctoptosis due to sinking of qi of the middle-jiao,
it is wise to choose lifting drugs to invigorate qi and lift yang.
Tue lifting,
lowering, floating and sinking actions of drugs have close relationship with their
properties and flavors. Most drugs that are pungent or sweet in flavor and warm
or hot in property have lifting and floating actions, whereas most drugs, bitter,
sour, or salty in flavor and cold or cool in property have lowering and sinking
actions. The lifting, lowering, floating and sinking actions also have some relationship
with the textures of drugs. Generally speaking, most of the light substances have
the actions of lifting and floating. In contrast, most of the heavy drugs have
the actions of lowering and sinking. However, though some drugs are light, they
have lowering and sinking actions; and conversely, some heavy drugs have lifting
and floating actions. In addition, the lifting, lowering, floating and sinking
actions can also be influenced or even altered through the processing and the
joint use of drugs. For example, lowering and sinking drugs can have lifting and
floating actions after processing with wine, while lifting and floating drugs
can have lowering and sinking actions after preparation with salt solution. If
lifting and floating drugs are dispensed together with a great amount of lowering
and sinking drugs, they may also have lowering and sinking actions; and similarly,
when lowering and sinking drugs are used together with a great amount of lifting
and floating drugs, they may exhibit some lifting and floating character.
3.
Channel Tropism
Channel tropism refers to a drug's selective therapeutic effects
on a certain part of the body. A drug may exert obvious or specific therapeutic
action on the pathological changes in a certain channel (including some viscera
thereof) or several channels, but with little effects on the others. For instances,
among the heat-clearing drugs, some only clear the heat either in the lung channel
or in the liver channel or in the heart channel, etc. Again, among the tonics,
some strengthen the lung while others strengthen the spleen or the kidney. Channel
tropism is based on the theory of viscera, the theory of channels and collaterals,
and is summed up according to the curing particular diseases for which a drug
is effective.
The human body is an organic whole in which the channels and
collaterals link up with the interior and exterior and all parts of the body.
A pathological change in the exterior may affect the viscera while diseases in
the viscera may, in turn, find expressions in the exterior of the body. For this
reason, the symptoms and signs of diseases occurring in different parts of the
body can be understood systematically according to the theory of channels and
collaterals. For instance, the flaring up of stomach-fire may result in swollen
gum; and whenever there is stagnation of liver-qi, pain in the hypochondriac region
will be present. Since the swelling and pain of the gum disappear when gypsum
is administrated, and hypochondriac pain relieved with 'the use of bupleurum root,
we may infer that gypsum acts on disorders of the stomach channel and bupleurum,
the liver channel. The above examples show that the theory of channel tropism
is summed up through clinical practice.
The channel tropism theory should be
associated with the theories of the four properties and five flavors, and actions
of lifting, lowering, floating and sinking of drugs. Different drugs acting on
the same channel have different effects owing to their different properties, flavors
and actions of lifting, lowering, floating and sinking. For example, scutellaria
root, dried ginger, lily bulb, and lepidium seed all act on the lung channel,
but scutellaria root can clear lung-heat, dried ginger can warm lung-cold, lily
bulb can be used to make up for lung deficiency, and lepidium seed is used to
soothe excess syndrome of the lung. Therefore, only when attention is paid to
the different aspects of a drug, can its actions be comprehensively analyzed and
the drug correctly employed. Besides, according to the theory that viscera as
well as channels and collaterals are physiologically related to one another, and
pathologically affect one another, when there is pathological change in one channel,
drugs acting on other channels should be used in addition to the prescription
for the diseased channel itself. For instance, for abnormalities in the lung channel,
drugs for strengthening the spleen channel should be added, and in case of hyperactivity
of the liver yang, drugs for nourishing the kidney-yin should be used at the same
time.
Extracted from "The Chinese Materia Medica"