What is Ephedra?

Ephedra is a naturally-occurring substance derived from the herb Ma Huang, which has been used by the Chinese to treat respiratory conditions for over 5,000 years. Named by some experts as the oldest medicinal plant in continuous use, ephedra comes from one of the three species grown in China: Ephedra sinica, Ephedra equisentina, Ephedra intermedia. In its synthetic form, ephedrine is regulated as a drug and is used as a decongestant for the short-term treatment of asthma, bronchitis, and allergic reactions.

The active components of ephedra are the ephedrine alkaloids, which include (-)-ephedrine, (+)-pseudoephedrine, (-)-norephedrine, and (+)-norpseudoephedrine. Growing conditions, such as geographic location, altitude, and soil pH, as well as species determine the alkaloid content and composition. Ephedrine accounts for up to 90% of the total alkaloid content, with pseudoephedrine following behind.

The pharmacology of ephedrine was not discovered until the early 20th century by Western medicine. Ephedrine is a mixed sympathomimetic agent, which acts indirectly via release of norepinephrine from sympathetic neurons and directly via stimulating alpha and beta adrenergic receptors. Hence, the pharmacologic activity of a certain ephedra sample is based on its alkaloid composition.

The physiological effects of ephedrine influence the cardiovascular, respiratory, and central nervous systems. Ephedrine increases heart rate and thus cardiac output. It also increases blood pressure via its peripheral vasoconstriction activity, which is dose-dependent in humans. Within the lung, ephedrine acts via beta-2 adrenergic receptors to relax bronchial smooth muscle, leading to bronchodilation. In the central nervous system, ephedrine acts as a stimulant, leading to improved mood, heightened alertness with decreased fatigue, and increased physical activity. These effects can be attributed to the stimulation of dopamine release and the increased release of central norepinephrine. At higher doses, the release of norepinephrine via ephedrine causes anxiety, restlessness, and insomnia.

In addition to the above physiological effects, ephedrine and its alkaloids may aid in weight loss via several mechanisms. In the hypothalamus, ephedrine may exert an anorexic effect via norepinephrine influence on the satiety centers. Also, lipogenesis increases with release of catecholamines via stimulation of beta-3 receptors in brown fat. And finally, ephedrine is a potent thermogenic agent, which leads to an increased dissipation of calories as heat as opposed to energy storage.