EPHEDRA (ma huang)
Ephedra (ma huang), together with its principal alkaloid ephedrine, was perhaps the first of the Chinese herbal remedies to see significant use in Western medicine. Known in China for more than 5,000 years, the green stems of various Ephedra species, particularly E. sinica Stapf, E. equisetina Bunge, and others of the family Ephedraceae, were employed there, and E. gerardiana Wall. was used in India for the treatment of bronchial asthma and related conditions.
The active constituent, ephedrine, was isolated by a Japanese chemist, N. Nagai, in 1887. However, it was not until 1924 when K. K. Chen and his mentor C. P. Schmidt, working at Peking Union Medical College, began to publish a series of papers on its pharmacological properties that physicians in this country began to appreciate the utility of the medication. Ephedrine became widely used as a nasal decongestant, a central nervous system stimulant, and a treatment for bronchial asthma. Other alkaloids, pseudoephedrine, norephedrine, norpseudoephedrine, etc., with similar but not identical properties, were subsequently found in various Ephedra species.
Studies on the herb revealed that the approximately forty species of Ephedra could be divided into several geographic types which seem to vary qualitatively and quantitatively in their alkaloid content. The significant finding regarding these types is that the North and Central American types all appear to be alkaloid free. Thus, any activity attributed to these species must result from compounds other than ephedrine or its derivatives. For that reason, species such as E. nevadensis (see Mormon tea) are not considered to be in this group of ephedra plants and are discussed elsewhere. It should be noted that Ephedra species are often extremely difficult to distinguish from one another, even for the specialist.
Ephedra is a potent and useful herb for relieving the constriction and congestion associated with bronchial asthma. Ephedra is an effective nasal decongestant and is used in the treatment of various allergic disorders in adults. Ephedra acts as a strong central nervous system stimulant, but despite the claims of some advocates, there is no substantial clinical evidence that it is either a safe or effective promoter of weight loss in obese persons or an enhancer of athletic performance. Unfortunately, ephedra and its contained ephedrine also increase both systolic and diastolic blood pressure. It also increase the heart rate and may cause palpitations as well as nervousness, headache, insomnia, and dizziness. Although the herb may be a very useful one in the treatment of various asthmatic and congestive conditions, the side effects indicated render its indiscriminate use highly inadvisable, particularly in persons suffering from heart conditions, hypertension, diabetes, or thyroid disease.
Because ephedrine can serve as precursor for the illegal synthesis of methamphetamine or "speed," a common medication of abuse, several states have passed laws regulating the sale of the alkaloid or products containing it. Although various species of ephedra contain 0.5 to 2.5 percent of an alkaloid mixture, some 30 to 90 percent of which is ephedrine, it must be emphasized that the herb is no longer the principal source of commercial ephedrine. That compound is produced today by chemical synthesis involving the reductive condensation of L-1-phenyl-1-acetylcarbinol with methylamine. This yields the desired isomer L-ephedrine, which is identical in all respects to the alkaloid obtained from ephedra. In view of the difficulties involved in extracting the relatively small concentrations of ephedrine from ephedra, and the fact that the plant serves only as a minor source of the alkaloid anyway, restricting availability of the herb on this basis, although certainly well-intended, seems an excessive measure. The fact that ephedra is commonly abused by consuming excessive amounts for its psychotropic effects is a far better reason for restricting its sale to adults only and limiting the dosage and duration of consumption.
- Traditionally, Zen monks used ephedra to promote calm concentration during meditation.Chinese herb
- In China, ephedra is popular for chills and fevers, coughs, and wheezing, and in combination with rehmannia is given to treat kidney yin deficiency.Current Western uses
- Ephedra is used principally in current Western herbal medicine as a treatment for asthma and hay fever, and for the acute onset of colds and flu. Ephedra also helps to raise blood pressure, cool fevers, and alleviate rheumatism.Other medical uses
- Chronic Obstructive Pulmonary Disease.