ABSTRACT
Ephedra (ma huang) is the common name for a herbal product used in traditional Chinese medicine. It comprises the aerial parts of three principal plant species: Ephedra sinica Stapf, E. equisetina Bunge, and E. intermedia var. tibetica Stapf.[1-3] The plant is a natural source of the alkaloids ()-ephedrine and (þ)-pseudoephedrine.[1]
GENERAL DESCRIPTION
E. sinica Stapf is a low evergreen shrub with small scaly leaves. It flowers in June and July and produces fruit late in the summer.[4] Approximately 45-50 species of ephedra have been described worldwide, including in the temperate and subtropical regions of Asia, Europe, and the Americas.[2,5] Most of those native to North, South, and Central America, such as E. nevadensis (used to make Mormon tea), E. trifurca, and E. antisyphilitica, contain no alkaloids.[5]
Most commercial uses of ephedra are based on its content of ephedrine, the main active constituent in the ephedra species known as ma huang.[1] Alkaloid content increases as the plant matures, with peak concentrations in the fall.[6] No ephedrine-type alkaloids are found in the roots, berries, or seeds of these plants, and the green upper parts of the stems contain significantly more alkaloids than the woody parts.[6]
Traditionally, ephedra has been administered as a tea prepared by soaking 2 g dried aerial portions in 8 fluid oz of boiling water for 10 min, ideally resulting in a content of 15-30 mg ephedrine. In commercial products, it is usually a formulation of powdered aerial portions or a dried extract.[7] The ephedrine content of such products ranges from 12 to 80 mg per serving, with most of them being in the lower part of the range.[8]
In the United States, ephedra was sold as a dietary supplement until April 2004 when the U.S. Food and Drug Administration (FDA) banned the sale of dietary
supplements containing ephedrine alkaloids. As defined by Congress in the Dietary Supplement Health and Education Act, which became law in 1994, a dietary supplement is a product (other than tobacco) that is intended to supplement the diet; contains one or more dietary ingredients (including vitamins, minerals, herbs or other botanicals, amino acids, and other substances) or their constituents; is intended to be taken orally as a pill, capsule, tablet, or liquid; and is labeled on the front panel as being a dietary supplement.
