Acute Hemorrhagic Myocardial Necrosis and Sudden Death of Rats Exposed to a Combination of Ephedrine and Caffeine

• Published in: Toxicological sciences 2005-02, Vol.83 (2), p.388-396
• Main Authors: Nyska, Abraham, Murphy, Elizabeth, Foley, Julie F., Collins, Bradley J., Petranka, John, Howden, Reuben, Hanlon, Paul, Dunnick, June K.
• Format: Article
• Language: English
• Subjects: Acute Disease; Administration, Oral; Adrenergic Agents - toxicity; Animals; apoptosis; caffeine; Caffeine - administration & dosage; Caffeine - toxicity; cardiotoxicity; Caspase 3; Caspases - metabolism; Central Nervous System Stimulants - administration & dosage; Central Nervous System Stimulants - toxicity; coagulative necrosis; Death, Sudden - etiology; Drug Combinations; Drug Interactions; ephedrine; Ephedrine - administration & dosage; Ephedrine - toxicity; Heart - drug effects; Hemorrhage - chemically induced; Hemorrhage - pathology; ischemia; Male; Myocardial Infarction - chemically induced; Myocardial Infarction - metabolism; Myocardial Infarction - pathology; Myocardium - metabolism; Myocardium - pathology; Necrosis; Rats; Rats, Inbred F344; Staining and Labeling
• ISSN: 1096-6080; 1096-0929; 1096-0929
• DOI: 10.1093/toxsci/kfi034

Because of possible side effects of herbal medicines containing ephedrine and guarana-derived caffeine, including increased risk of stroke, myocardial infarction, and sudden death, the Food and Drug Administration recently banned the sale of ephedra-containing products, specifically over-the-counter dietary supplements. We report cardiac in 7- and 14-week-old male F344 rats exposed by gavage to ephedrine(25 mg/kg) and caffeine (30 mg/kg) administered in combination for one or two days. The ephedrine-caffeine dosage was approximately 12- and 1.4-fold, respectively, above average human exposure, based on a mg/m2 body surface-area comparison. Several (5/7) of the exposed 14-week-old rats died or were sacrificed in extremis 4–5 h after the first dosing. In these hearts, changes were observed chiefly in the interventricular septum but also left and right ventricular walls. Massive interstitial hemorrhage, with degeneration of myofibers, occurred at the subendocardial myocardium of the left ventricle and interventricular septum. Immunostaining for cleaved caspase-3 and hyperphosphorylated H2A.X, a histone variant that becomes hyperphosphorylated during apoptosis, indicated multifocal generalized positive staining of degenerating myofibers and fragmenting nuclei, respectively. The Barbeito-Lopez trichrome stain revealed generalized patchy yellow myofibers consistent with degeneration and/or coagulative necrosis. In ephedrine-caffeine-treated animals terminated after the second dosing, foci of myocardial degeneration and necrosis were already infiltrated by mixed inflammatory cells. The myocardial necrosis may occur secondarily to intense diffuse vasoconstriction of the coronary arterial system with decreased myocardial perfusion. Our work shows the direct relationship between combined ephedrine and caffeine exposure and cardiac pathology.