Ma Huang and the Ephedra Alkaloids

Steven B. Karch

Summary

Ephedra has been used as a natural medicine for thousands of years by numerous cultures with very little concern about toxicity. Its most recent popularity is related to its purported "weight loss" or "performance enhancing" attributes. In spite of that in 2004, concerns over safety resulted in the banning of all over-the-counter (OTC) sales of ephedra-containing dietary supplements by the Food and Drug Administration.

All ephedra plants contain phenylalanine-derived alkaloids, including ephedrine, pseu-doephedrine, methylephedrine, and trace amounts of phenylpropanolamine. Previously marketed herbal supplements typically stated total ephedra alkaloid content, although actual levels of individual alkaloid varied depending on raw material and production runs.

A double-blind, placebo-controlled trial by Boozer et al. examined issues of long-term safety and efficacy of ephedra, demonstrating its ability to reduce body weight and body fat while improving blood lipids without significant adverse events. Although other studies have documented a favorable adverse effect profile for appropriately administered doses of ephedra-con-taining supplements, there have been numerous anecdotal reports of adverse effects. Abuse and misuse of ephedra-containing products likely contributed to spontaneously reported adverse effects and increased concerns over safety.

As with other sympathomimetic agents, theoretical drug interactions with ephedra alkaloids are possible. Despite this potential, only a handful of adverse drug interactions have been reported. This is especially pertinent when considering the extensive use of both ephedra-con-taining supplements and ephedrine- or pseudoephedrine-containing OTC products. The most notable interaction exists between nonselective monoamine oxidase inhibitors and ephedra- or ephedrine-containing products.

From Forensic Science and Medicine: Herbal Products: Toxicology and Clinical Pharmacology, Second Edition

Edited by: T. S. Tracy and R. L. Kingston © Humana Press Inc., Totowa, NJ

With the ban of ephedra-containing dietary supplements and severe restrictions in access to ephedrine-containing OTC products, the landscape of clinical use associated with agents of this nature has been dramatically changed forever. Interest in further clinical study will likely be severely limited.

Key Words: Herbal stimulants; weight loss; phenylalanine; alkaloids; bronchodilator; athletic performance.

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