The quest for effective weight loss solutions has led to the proliferation of various dietary supplements. Among these, Xenadrine has gained considerable attention. This article delves into the ingredients of Xenadrine, its purported effectiveness, and the safety concerns associated with its use, especially in light of the ban on ephedra-containing products.
Introduction
Following the ban on ephedra, a substance linked to serious cardiovascular events and fatalities, many weight-loss aids have emerged as replacements. However, concerns have been raised regarding the safety and effectiveness of these ephedra-free alternatives, including Xenadrine.
Xenadrine Ingredients
Xenadrine EFX contains extracts of bitter orange, known scientifically as Citrus aurantium. The botanical, which has long been used in traditional Chinese medicine for digestive problems, has emerged as one of the major replacements for ephedra in over-the-counter weight-loss products. Citrus aurantium contains a compound called synephrine that, like ephedra, stimulates the central nervous system and may boost metabolism. Xenadrine RFA contained 335 mg of ma huang (ephedra alkaloid) and 910 mg of guarana seed (equivalent to caffeine) per recommended dose.
Concerns about Cardiovascular Effects
Research indicates that some ephedra-free diet supplements, including Xenadrine EFX, may carry risks of their own. A study conducted at the University of California, San Francisco, revealed that Xenadrine EFX increased the heart rates of healthy volunteers and also raised their blood pressures.
In the study, Xenadrine boosted volunteers’ blood pressure by between 9 and 10 points, on average. With Xenadrine EFX, participants showed elevated heart rates 6 hours after taking the supplement. The Xenadrine product contained a mix of bitter orange extract, caffeine and various herbs -- pointing to the combined effects as the culprit behind the blood pressure elevation.
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These cardiovascular effects may not pose a problem for healthy people. The concern is with those who have elevated blood pressure, or conditions such as diabetes -- as many overweight and obese people do.
Ephedra and Cardiovascular Risks
Ephedra alkaloids are naturally occurring stimulants that are widely used to enhance athletic performance and to promote weight loss. These substances have been associated with adverse cardiovascular events, including acute myocardial infarction, severe hypertension, myocarditis, and lethal cardiac arrhythmias. They have also been reported to predispose patients to hemorrhagic and ischemic strokes.
Case Study: Myocardial Infarction and Xenadrine RFA
In September 2002, a 24-year-old man presented at the emergency room of our institution with acute onset of left precordial chest pain that radiated to the left arm, accompanied by numbness of the left arm and hand. The pain occurred during exercise. There was no family history of premature coronary artery disease. The patient had no history of chest trauma, diabetes, hypertension, hypercholesterolemia, smoking, or alcohol consumption.
Emergent coronary angiography revealed total occlusion of the proximal left anterior descending artery. No underlying atherosclerotic lesions were found, and the left and right coronary systems appeared to be free of atherosclerosis. Persistent occlusion of the apical portion of the anterior descending artery was attributed to embolization of the proximal thrombus despite AngioJet thrombectomy, distal angioplasty, and intracoronary infusion of both nitroglycerin and adenosine.
This young, active, previously healthy body builder had an acute myocardial infarction in the absence of structural heart disease or known risk factors for coronary artery disease. Coronary angiography revealed thrombotic occlusion of the anterior descending artery with no demonstrable underlying atherosclerotic plaque and no evidence of active coronary spasm. The myocardial infarction was likely caused by in situ coronary thrombosis, perhaps related to transient coronary spasm and transient platelet activation as a result of intense sympathetic activity.
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Xenadrine RFA contained 335 mg of ma huang (ephedra alkaloid) and 910 mg of guarana seed (equivalent to caffeine) per recommended dose.
Ma Huang and Cardiovascular Effects
Ma huang increases the availability of catecholamines at adrenergic synapses in the brain and in the heart, directly stimulating α- and β-adrenergic receptors. As a result, the heart rate increases and the blood pressure rises secondary to elevated cardiac output and peripheral resistance. The combined effects of caffeine and ephedra increase myocardial oxygen consumption by increas-ing heart rate, contractility, and peripheral resistance (afterload), while potentially diminishing coronary blood flow by increasing coronary resistance and promoting frank coronary spasm. The diminished blood flow may lead to the development of in situ thrombosis.
FDA Actions and Concerns
Although the FDA's adverse event reporting system has served a useful purpose in drawing attention to the potential public health concerns over Xenadrine RFA and similar over-the-counter preparations, the FDA was initially somewhat slow to react. In December 2003, however, the FDA announced that it would be removing ephedra from the market place, and the final ruling went into effect on 12 April 2004. This was the 1st time that the FDA had banned an herbal supplement.
The Importance of Caution and Further Research
Until more is known about the safety and efficacy of herbal diet aids, people should not assume that ephedra-free means risk-free. People perceive these products as “natural,” and therefore safe.
The scientists call for longer term dosing studies to determine whether the blood pressure effects of Xenadrine EFX persist with repeated use.
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