What is the dermatologic preoperative evaluation and management of ephedra?

Updated: Mar 16, 2020
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Ephedra is used to promote weight loss; to increase energy; and to treat respiratory tract conditions, such as asthma and bronchitis. It contains alkaloids, including ephedrine, pseudoephedrine, norephedrine, methylephedrine, and norpseudoephedrine. Ephedra causes dose-dependent increases in blood pressure and heart rate. Ephedrine, the predominant active compound, is a noncatecholamine sympathomimetic agent that exhibits alpha1, beta1, and beta2 activity by acting directly on adrenergic receptors and by indirectly releasing endogenous norepinephrine. These sympathomimetic effects have been associated with more than 1070 reported adverse events, including fatal cardiac and CNS complications.

Ephedrine is widely used as a first-line therapy for intraoperative hypotension and bradycardia; the unsupervised preoperative use of ephedra raises certain concerns. Vasoconstriction and vasospasm of coronary and cerebral arteries may cause myocardial infarction and thrombotic stroke. Patients who have consumed ephedra and are anesthetized with halothane may be at risk of intraoperative ventricular arrhythmias because halothane sensitizes the myocardium to ventricular arrhythmias caused by exogenous catecholamines. Ephedra may affect cardiovascular function by causing hypersensitivity myocarditis characterized by cardiomyopathy with myocardial lymphocyte and eosinophil infiltration.

The long-term use of ephedra causes tachyphylaxis from the depletion of endogenous catecholamine stores and may contribute to perioperative hemodynamic instability. In these situations, direct-acting sympathomimetic agents may be preferred as first-line therapy for intraoperative hypotension and bradycardia. The concomitant use of ephedra and monoamine oxidase inhibitors can result in life-threatening hyperpyrexia, hypertension, and coma. In addition, the heavy use of ephedra has been documented to cause radiolucent kidney stones. Ephedra used as an appetite suppressant has resulted in numerous deaths and FDA regulation is forthcoming.

The pharmacokinetics of ephedrine have been studied in humans. Ephedrine has an elimination half-life of 5.2 hours, with 70-80% of the compound excreted unchanged in the urine. Based on the pharmacokinetic data and the known cardiovascular risks of ephedra, patients taking this herb should discontinue use at least 24 hours prior to surgery.


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