The effect of sodium bicarbonate on propranolol-induced cardiovascular toxicity in a canine model

Study Objective: To evaluate the potential utility of sodium bicarbonate in an established model of acute propranolol toxicity. Methods: Two minutes a fter the completion of a propranolol infusion (10 mg/kg), a bolus of 1.5 mE q/kg of sodium bicarbonate solution (1 mEq/mL) followed by an infusion of 1 .5 mEq/kg over the next 26 minutes (n = 6) or an equivalent timing and volu me of 5% dextrose solution (n = 6) was administered in each dog. Targeted c ardiovascular parameters included heart rate, mean arterial pressure, left ventricular dP/dt(max), and QRS interval. Results: Propranolol infusion sig nificantly depressed heart rate (p < 0.0001), mean arterial pressure (p < 0 .0001), dP/dt(max) (p < 0.0001) and prolonged the QRS interval (p < 0.0001) . Sodium bicarbonate failed to significantly improve these targeted paramet ers when compared to control animals. Conclusion: In this canine model of p ropranolol toxicity, intravenous sodium bicarbonate appears to be an ineffe ctive single therapy. Furthermore, these results may suggest a different me chanism of sodium channel blockade for propanolol than that of type IA anti arrhythmic agents.