Experimental treatment of the acute cardiovascular toxicity of caffeine

Study Design: The intravenous infusion of caffeine-sodium salicylate (15 mg/kg/min) into artificially ventilated and anesthetized rats caused a progressive fall in arterial blood pressure which was mainly due to a decrease in peripheral resistance. Cardiac output increased initially by 15%, but then declined after 30 minutes. The electroencephalogram showed sinus tachycardia and ectopic beats mainly in the form of monomorphic ventricular bigeminy which began after 22.8 minutes. Fatal ventricular fibrillation occurred in all animals by 66.9±3.1 minutes. Treatment of cardiac arrhythmia by repeated intravenous injections of propranolol (1 mg/kg) or verapamil (1 mg/kg) was effective and prolonged survival time to 91.7±4.4 or 84.3±2.9 minutes, respectively (p<0.05). Propranolol also prolonged survival time when administered in a single dose of 20 mg/kg IV 10 minutes before the initiation of caffeine infusions. Repeated administrations of quinidine sulfate (5 mg/kg), phenytoin (5 mg/kg), or lidocaine (1–5 mg/kg...