Chinese Herbal Medicine
Chinese herbal medicine (CHM) is a general term that describes all traditional medicinal in China. Based on the theory of Traditional Chinese Medicine (TCM), CHM is characterized by its unique theoretical system and application norms, which is different from that of natural medicine. CHM includes botanical, zoological and mineral substances. A total of 12807 medicinal substances are available, of which 11146 are from plants, 1581 from animals, and more than 80from minerals. Since herbs are the vast majority of the most commonly used medicinal substances, Chinese herbal medicine has been know as Chinese materia medica since the ancient times.
CHM draws on long-term ancient practices by the Chinese people in production, life and medicine. Primitive people when hunting for food inevitably took some poisonous substances by mistake, causing vomit, coma or even death. Some substances nevertheless were found to help relieve disorders or cure diseases. A legend goes that “Shen Nong tasted one hundred herbs…experienced 70 kinds of poisonous herbs in one day”, which vividly portrays the accumulation of early medicine knowledge. Repeated trials and constant summarization contribute to the know-how of early pharmacotherapy. Many plants have become remedies when used purposefully to treat diseases, as is also the case whit the discovery of animal and mineral substances.
Four properties – cold, hot, warm and cool:
Four properties (cold, hot, warm, and cool) refer to the nature of medicinal. Cold and cool attribute to yin while warm and hot to yang. With the property of medicinal yin and yang are regulated and balance is restored. Theoretically, if the disease is cold in nature, medicinal hot in property are given, and vice versa. For instance, a patient with high fever, extreme thirst, flushed face, red eyes, swollen sore throat, and surging pulse should be diagnosed as the yang-heat pattern, and accordingly, such cold-natured medicinal as Shigao (Gypsum), Zhimu (Common Anemarrhena Rhizome) and Zhizi (Cape Jasmine Fruit) should be administered. On the contrary, a patient with cold limbs, pale complexion, cold pain in the stomach and faint pulse can be concluded as the yin-cold pattern, and preferably, Fuzi (Prepared Common Monkshood daughter root), Rougui (Cassia Bark), and Ganjiang (Dried Ginger) should be used since they are warm and hot in nature.
Five flavors – sour, bitter, sweet, acrid and salty:
The five flavors refer to the five tastes of Chinese medicinal, i.e. sour, bitter, sweet, acrid and salty. A flavor not only describes the taste of a medicinal substance but also the effect it produces. For instance, acrid substances disperse cold and stagnation, move qi and blood, so Shengjiang (Ginger) is used to treat common cold due to wind-cold. Sweet substances acts to tonify, regulate the stomach, moderate herbal properties and relieve convulsion and pain, so Gancao (Liquorice Root) is used for stomach-spleen weakness and reducing toxicity of medicinal substances. Sour substances act to astringe and arrest discharge, so Wumei (Smoked Plum) is used for persistent coughing due to long-qi deficiency as well as chronic diarrhea and dysentery. Bitter substances act to purge fire, clear heat, relax bowels, and eliminate dampness, so Dahuang (Rhubarb) is used to treat constipation due to heat retention and boils due to toxic-heat. Salty substances act to purge and relieve constipation, soften hardness and dissipate nodulations, so Haizao (Seaweed) is used for goiter, tumor, scrofula and beriberi.
Processing of medicinal substances is listed among the intangible cultural heritages in China. Herbs usually need to be processed into “prepared slices” via cleaning, cutting and processing with auxiliary materials before they are used as medicines. Common preparation includes selecting, washing, rinsing, slicing, steaming, boiling, scalding, etc… Auxiliary materials such as alcohol, ginger, wheat bran, salt, honey and vinegar are conventionally utilized. As the most commonly used method, cutting makes active constituents soluble during making a decoction.
Function of processing:
Processing can alter the medicinal properties to suit different therapeutic needs. For example, Xiaodihuang (Fresh Rehmannia Root) is sweet and bitter in flavor, and extreme cold in property. Shengdihuang (Raw Rehmannia Root) is sweet in flavor and cold in property, while Shudihuang (Prepared Rehmannia Root) is sweet in flavor and warm in property. After processed, Shudihuang is no longer a medicament for heat clearing, but for enriching blood.
Processing can also reduce toxicity or side effect to ensure safety. For example, after Wutou (Monskhood) is steamed, its toxic c constituent aconitine is hydrolyzed into benzoyl aconitum amine and aconitum amine, therefore, the toxicity of aconitine is greatly reduced.
Processing can improve therapeutic effects. For example, some herbs prepared with rice alcohol can enhance blood circulation to remove blood stasis, aid in expelling wind and dredging meridians. Herbs being stir-fried with ginger juice can enhance the action of eliminating phlegm to stop cough and descending adversely risen stomach-qi to stop vomit. Herbs processed with honey can facilitate relieving cough and panting, and tonifying the spleen to invigorate qi.
Composition of Formulas
Combination of herbal ingredients:
Medicinal herbs are often used in combination, i.e. putting two or more compatible herbs together in accordance with different conditions and different herbal properties. In combination with herbal ingredients, it is essential to focus on their actions, e.g. single effect, mutual accentuation, mutual assistance, mutual counteraction, mutual suppression, mutual antagonism and incompatibility. Mutual accentuation and mutual assistance strengthen the herbs’ effects, mutual counteraction and mutual suppression inhibit the toxicity of herbs, while mutual antagonism and incompatibility can weaken the herbs’ effects or generate toxicity that accordingly needs to be avoided in combination of herbal ingredients.
Rules for formula composition:
Formula composition is not as simple as the addition of herbs but has its own rules and principles. Monarch, minster, assistant and envoy are the principle ancient people follow to formulate prescriptions. The monarch is the formula, usually strong in action and large in dosage, addresses the major complaints and plays the major therapeutic role. The minister assists the chief herb in its function. The assistant herb on the one hand reinforces the effects of the chief herb to treat concomitant patterns, on the other hand it reduces or eliminates the side effects of the chief herb. The envoy either directs the herbs in the formula to the diseased site, or harmonizes the other herbs in the formula.
Administration of Medicinal Herbs
Chinese medical formulas have been developed into various dosage forms for oral administration or external application during long-term medical practice. The forms include decoction, medicated wine, medicated tea, distillate, pill, powder, soft extract, vermillion pill, tablet, lozenge, jelly, leaven, medicated roll and medicated thread. Among them, decoction is the major available form and still extensively used in TCM clinical practice because flexible modifications can be mad in accordance with the conditions. Moreover, decoction made it easier for human body to absorb, and thus takes effects faster.
In recent years, with the development of modern pharmaceutics and related science and technology, Chinese patent medicines are made available in various forms such as capsules, granules, injections, aerosols and drops. Thanks to the application of microcapsule, sustained-release preparation and target preparation technology, modern preparation technology is aiming at quantification, timing, location, and reduction of adverse effects in conjunction with achieving high efficiency and quick yet long-term effects.