Posting Date: 05/20/2002
Ma huang, Chinese ephedra, was used to treat asthma, or at least wheezing, five thousand years ago.
The Herbal Classic of the Divine Plowman described it as an herb of "middle class," referring to its perceived usefulness rather than to a social standing. It has been part of the Chinese herbal pharmacopoeia ever since, and Chinese scientists (K. K. Chen and his colleagues) did some of the early research into its pharmacology early in the twentieth century.
The active component isolated from E. sinica, ephedrine, was a staple of standard medical management of asthma in the United States for several decades.
Although it has been replaced for the most part with newer synthetic compounds, ephedrine is still available over the counter for nasal congestion (as a spray or jelly) and in capsules with or without prescription as a bronchodilator.
There are many species of ephedra, but not all of them contain ephedrine or other active compounds. A native of the American Southwest, E. nevadensis, or Mormon tea, is one that does not.
The part of E. sinica that is used is the dried stem. The roots and the fruits have little or no ephedrine or other alkaloids.
The primary active ingredient of ma huang is ephedrine, accounting for 80 to 90 percent of the alkaloid content of the plant.
It also contains related chemicals, such as pseudoephedrine, which is also used in medicines to relieve nasal congestion.
In China, ma huang was used traditionally to cause sweating and to treat colds and other nasal congestion (most likely due to allergy). E. sinica could still be used to treat coughs and colds, but the synthetic derivatives are readily available in easily controlled doses.
Ephedrine is still used sometimes to treat an acute attack of asthma.
Ephedrine relaxes bronchial muscle but constricts small blood vessels in the arms and legs. This raises blood pressure, an action that is sometimes put to use in treating shock.