Since the US government's ban on ephedra-based products, there has been an obvious decline in its prevalent use in that country. However, patients may still present for pain evaluation with a history of use of ephedra or be taking related compounds, many of which are readily available and possess potent dose-dependent increases in heart rate and in blood pressure. Ma huang, an ephedra-based alkaloid, is similar in structure to amphetamines and is traditionally indicated for the treatment of various respiratory disorders such as the flu, common cold, allergies, and bronchitis. Additionally, it is commonly used as an appetite suppressant (Hughes et al. 2004). Ma huang or ephedra acts as a sympathomimetic agent and exhibits potent positive inotropic and chronotropic responses. In addition to its antitussive actions, ephedra may also possess bacteriostatic properties (Kaye et al. 2000). As a cardiovascular and respiratory sympathomimetic, it utilizes an a-adrenergic or ^-adrenergic sensitive pathway (Tinkleman and Avner 1977). Recent laboratory data using the cat lung vascular bed indicate that ephedra-mediated pulmonary hypertension is dependent upon a(1)-adrenoreceptor sensitive mechanisms (Fields et al. 2003).
The appetite suppressant and metabolic enhancer effects of ma huang made it a potent ingredient of various over-the-counter weight loss compounds. However, even prior to the United States' federal ban on ma huang, many herbal manufacturers were already promoting their ephedra-free supplements due to the numerous reported adverse effects of ephedra.
Dangerous side effects of ma huang administration include systemic hypertension, pulmonary hypertension, tachycardia, cardiomyopathy, cardiac dysrhythmias, myocardial infarction, stroke, seizures, psychosis, and death (Hughes et al. 2004). Many of these complications have been attributed to a lack of standardization in its formulation (Gurley et al. 1998 and MMWR 1996). Prior to the United States' federal ban of ma huang, approximately 16,000 cases of adverse events including 164 deaths had been reported to the United States Food and Drug Administration (FDA) since 1994 (Jurgensen and Stevens 2004). Further, The Bureau of Food and Drug Safety of the Texas Department of Health reported eight ephedra-associated fatalities during a 21-month period between 1993 and 1995; seven of the fatalities secondary to myocardial infarction or stroke (Leak 1999). There have also been a number of large groups of lawsuits for ephedra-linked myocardial infarction, stroke, and pulmonary hypertension in recent years. Patients at highest risk of side effects include those who are pregnant, have hypertension, coronary vascular disease, seizures, glaucoma, anxiety, or mania (Hughes et al. 2004).
The use of ma huang, still available over US borders, is highly relevant to the pain practitioner in the perioperative period. The possibility of hypertension causing myocardial ischemia or stroke needs to be considered. Further, ephedra or similar compounds readily available over the counter can potentially interact with general anesthetic agents, such as halothane, isoflurane, desflurane, or cardiac glycosides, like digitalis, to cause cardiac dysrhythmias. Patients taking ephedra for prolonged periods of time can also deplete their peripheral catecholamine stores. Therefore, under general anesthesia, these patients can potentially experience profound intraoperative hypotension which can be controlled with a direct vasoconstrictor (e.g., phenylephrine) instead of ephedrine. Finally, use of ephedra with phenelzine or other monoamine oxidase inhibitors may result in insomnia, headache, and tremulousness and concurrent use with the obstetric drug oxytocin has been resulted in hypertension (Grontved and Hentzer 1986).
Was this article helpful?
Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...