ERMIAO SAN: TWO MARVELS POWDER
Ermiao San is a frequently mentioned formula both in texts describing traditional prescriptions and in modern clinical reports. Its name, two marvels powder, is explained in Chinese Herbal Medicine Formulas and Strategies (1): "The formula is considered to be a 'marvel' for its simplicity and its singular effectiveness." The formula, comprised of two herbs, was recorded in Danxi Xinfa (Teachings of Zhu Danxi), published in 1481. Zhu Danxi (1281-1358) was a famous doctor of the Jin-Yuan Medical Reform period. Although this formula was not much relied upon during the subsequent centuries, it became prominent beginning in the latter half of the 20th Century when clinical research confirmed the potent actions that were implied by its name.
The formula is comprised of equal amounts of phellodendron (huangbai) and red atractylodes (cangzhu) ground to powder and swallowed down with ginger juice (if available; otherwise with water). In modern materia medica guides, phellodendron is classified with the herbs that clear heat and dry dampness; it is bitter and cold; red atractylodes is classified with the aromatic herbs that resolve moisture accumulation; it is spicy and warm, with some bitterness. Together, they dry dampness and treat a syndrome of damp heat, dispersing swelling and alleviating pain due to accumulation (2). In the traditional preparation, the herbs are fried, which is intended to yield a more drying effect. One of the principal indications for this formula is a disorder with yellow color: skin eruptions with pus, discharge that is discolored, dark yellow urine, yellow tongue coating, jaundice, and so on, though this coloration is not an essential requirement for use of the formula.
During the 1970s numerous reports emerged about the effectiveness of Ermiao San for treatment of exudative eczema, given orally or applied topically; reports of treatment of infants were included (3, 4). In the topical therapies, phellodendron was likely the main active component, serving as an antiseptic. Similar clinical use of phellodendron-alone and in formulas other than Ermiao San-was reported.
The lower body is the primary site of symptoms indicating Ermiao San for internal use, since the Chinese concept is that the excess dampness pulls the pathogenic heat downward. In this application, the formula can be compared to Longdan Xiegan Tang (Gentiana Liver Cleansing Decoction, or, simply, Gentiana Combination), which lacks the aromatic component, but clears heat and dampness with bitter tasting herbs. The combination of Longdan Xiegan Tang and Ermiao San is recommended in the book Practical Traditional Chinese Dermatology (6) for treatment of scrotal eczema or vulvar eczema when damp-heat syndrome is the main constitutional background to the disease. In Practical Therapeutics of Traditional Chinese Medicine (7), the combination of Longdan Xiegan Tang and Ermiao San is recommended generally for treatment of eczema where damp-heat is predominant, with symptoms of itching and exudation being typical. When local damp-heat manifests symptoms in a person with a constitutional background of yang deficiency, the recommended formula is the combination of Ermiao San with Erxian Tang (Two Immortals Decoction); the latter tonifies yang but clears deficiency heat; both formulas contain phellodendron.
Ermiao San is recommended in Chinese-English Manual of Commonly Used Prescriptions in Traditional Chinese Medicine (8) for "swelling, pain, and increased temperature over the knees and legs." Disorders of rheumatic or gouty arthralgia in the legs fit this description and are specific indications mentioned in the text. Further, damp-heat pouring downward to the legs is believed to impair the nervous system and muscles, leading to atrophy with numbness or pain.
Ermiao Wan (pills of Ermiao San) has become an official medicine in China, listed in the Pharmacopoeia of the PRC (9). It is indicated for: "Damp-heat in the lower part of the body, marked by redness, swelling, hotness, and pain in the legs and knees, erysipelas of the lower extremities, morbid leukorrhea, or wetness and itching of the scrotum." The dosage is 6-9 grams each time, twice a day.
In relation to its use in treatment of pain in the legs, the formula has been modified by subsequent medical scholars to produce a three-herb version (Sanmiao San) with achyranthes added; and a four-herb version (Simiao San) with further addition of coix. Achyranthes is employed to aid blood flow downward, thus making this formula especially useful for poor circulation in the feet, with numbness and burning pain. Coix helps eliminate dampness and is recommended in those cases where there is also swelling in the legs and feet.
Phellodendron is obtained from the bark of the tree Phellodendron amurense (see Figure 1) or, sometimes, Phellodendron chinense. The trees are cultivated in China to supply the huge demand for this frequently used herb. The main active components are alkaloids of the isoquinoline type, with berberine, palmatine, magnoflorine, phellodendrine, candicine, and jatorrhizine being the main ones. Berberine is one of the most extensively studied of these alkaloids; it constitutes about 1.7% of the dried bark from P. amurense. Berberine is also a key component of other Chinese herbs, including coptis and sankezhen (Berberis sp.). Berberine has been clinically evaluated in the treatment of diarrhea due to a variety of pathogens including bacterial infections and giardia; it is also used topically for treatment of bacterial eye infections, and applied orally to the treatment of bacteria that cause tooth decay. The alkaloids found in phellodendron, such as berberine and palmatine, have been isolated in relatively pure form (greater than 90% purity) for use in treatment of infections.
Atractylodes (cangzhu) is obtained from the rhizome of Atractylodes lancea (see Figure 2), or sometimes from A. chinensis; it is distinguished in Chinese medicine from the rhizome of A. macrocephala, which is the source of baizhu (white atractylodes), classified as a qi tonic herb. The main uses of cangzhu are treatment of digestive system disorders and arthralgia. Its main active components are essential oils; these comprise 3.5-5.6% of the dried rhizome of A. lancea. The principal constituent is beta-eudesmol, a sesquiterpene alcohol; other components are hinesol, elemol, atractylodin, selinene, and furaldehyde. Eudesmol is also a major component of magnolia bark (houpo), which is classified along with atractylodes as an aromatic herb for resolving moisture and which has similar uses for digestive system disorders. The pharmacology of the essential oil has not been worked out fully, but a clinical evaluation of the essential oil indicated that it was effective in treating pruritis, urticaria, allergic dermatitis, and exudative eczema.
Figure 2: Atractylodes lancea.