How Chinese Herbal Formulas are Put Together
The Huangdi Neijing says that "one that manages the main disease is the chief, on ethat supports the chief is the deputy, one that assists the deputy is the envoy."
Thus, the foundation is laid for the structure and organization of a Chinese herbal formula.
In western medicine, we tend to think of "one drug, one problem." A patient might be given one drug for hypertension, another for high cholesterol, and another for chronic pain. Very seldom are drugs seen as working in combination. Examples of these are the combination of amoxicillin and clavulanic acid, the combination of. sulfamethoxazole and trimethoprim combination, and the combination of piperacillin and tazobactam. These are antibiotic combinations where the two drugs together are more effective than either one alone.
Hence, it is not surprising that when the non-oriental mind studies Chinese medicine, the initial mentality is one of pure addition. Just like in western medicine, the temptation is one of thinking what each ingredient in a herbal formula does individually. Likewise, one can easily panic when looking at the side effect profiles of each ingredient in a herbal formula and think that they all add up commutatively as well.
The fact of the matter is that Chinese herbal formulas must be seen in the context in which it was developed. The earliest individual medicinal herbs were in fact referred to as "poisons" in obvious recognition that these medicines by themselves could have severe side effects. It was only later that the term 本草 (literally root and grass) or "herbal medicines" was used to refer to them.
So what changed, what evolved?
Quite simply, it is the use of herbals in formula form that enables Traditional Chinese Herbal Medicines to maximize therapeutic efficacy and reduce unwanted adverse effects.
The Chinese term for looking at how medicinals work together is "配伍" which translates into matching individuals to work as a team. One can use metaphors from team sports. Arnold "Red" Auerbach, patriarch of the National Basketball Association's Boston Celtics, used to say that the best teams are not made of the five best players, but the five players that play best together. The same applies in Chinese Herbal Medicines.
Let's take a look at how Herb combinations are done.
In the western medicine examples I gave above, the first method is seen: mutual enhancement. The medicines enhance each other in their germ killing properties. This is the most basic method of combining medicinals. Traditional Chinese Medicine has more.
Herbs in Chinese medicine are studied and their actions defined by pairs or groups. Let's take the example of 桂枝 （Gui Zhi) or Cinnamon Twig. Gui Zhi induces sweat and releases the exterior... when combined with 麻黄 (Ma Huang). Gui Zhi can harmonize the Yin and Wei... when combined with 芍药 (Shao Yao). Hence, part of combining is eliciting effects from the combination that the individual component may not have if given with other herbs.
Most importantly though, Chinese herbals are given in combination, and I cannot emphasize this enough, to reduce side effects.
I have recently discussed 莲花清瘟 or lianhua qingwen capsules. A colleague of mine was talking about one of the ingredients, which by itself is known to produce cardiac side effects. However, lianhua ITSELF is shown to have very little cardiac side effects. How is this possible? Simple. The individual herb is combined with other herbs to enhance the good effect and reduce the side effects.
Let us not go to exactly how a formula is composed. The quote I began this blog entry with talks about Chief, Deputy and Envoy. Today we have four roles:
Chief- The chief herb is the main herb in the formula. It sets the tone.
Deputy - The deputy herb either supports the chief by performing the same action, or treats a secondary pattern. For example, a chief might expel pathogens while the deputy strengthens the body.
Assistant - There are three kinds of assistants. The adjuvant again helps the chief and deputy. The restrictive assistant helps relieve side effects. The opposing adjuvant moderates the effect of the chief and deputy.
Envoy - The envoy either guides the formula to a specific location/meridian, or moderates the effect of the individual herbs so as to enable the formula to work.
Let's take a look at one of the most basic of formulas: 桂枝汤 Gui Zhi Tang. Gui Zhi Tang is used primarily for treating what we call the external invasion of Wind-Cold. Now, 麻黄汤 Ma Huang Tang is also used for this, so what' the difference? Ma Huang Tang is used with the Wind-Cold is merely lodged in the exterior, leading to symptoms of headache, chills, slight fever, nape stiffness, with no sweating. Ma Huang Tang induces sweating to push the Wind-Cold out. In modern medicine, we know that the sweating is a consequence of the body's systems resetting properly, not the cause, but I digress.
If there is sweating but no recovery, Chinese theory looks at it as the body being too weak to push the Wind-Cold totally out. Hence we have TWO problems - the Wind-Cold affecting the exterior that must be pushed out, and the interior weakness unable to push the Wind-Cold out even if with sweating. Hence, the formula for Gui Zhi Tang must cover these two concurrent problems. The western mind is tempted to use individual ingredients to resolve the two problems without caring how they affect each other. But we speak not of the western mind here.
On to the components of Gui Zhi Tang. The ingredients are Gui Zhi, Bai Shao, Sheng Jiang, Da Zao and Zhi Gan Cao.
Gui Zhi is the chief. It is warm in nature and strengthens Yang. In Ma Huang Tang, Gui Zhi is considered a deputy herb - it helps Ma Huang expel the pathogens. Here, it is the Chief, because the main problem is both expelling and nourishing, which Gui Zhi does.
Bai Shao's job is to prevent too much yin/fluid from leaking out. As a deputy, it seems to counteract Gui Zhi at first. The fact is that Bai Shao and Gui Zhi then serve to drive the Wind-Cold out by preserving the yin in the interior. There is a synergistic effect. Bai Shao will not do this by itself. Gui Zhi without Bai Shao might drain the yin too much.
Sheng Jiang and Da Zao are assistants. Sheng Jiang helps Gui Zhi warm the interior and covers organs/meridians that Gui Zhi does not. Da Zao helps Bai Shao in strengthening the yin.
Finally, Zhi Gan Cao harmonizes the formula as the envoy.
I have thought of analyzing Lianhua Qingwen here, but that formula deserves a blog entry of it's own.
Hence, whenever we study Chinese Herbal Formulas, understanding the formula using the roles set above helps us to understand how it works and helps us understand how to modify the formula in order to achieve a different goal.