Hypotensive action of commercial intravenous amiodarone and polysorbate 80 in dogs.

Commercial intravenous amiodarone has been reported to have antiarrhythmic actions and to cause only mild hypotension in humans. In the dog, however, amiodarone was observed to cause severe hypotension. Since commercial intravenous amiodarone is amiodarone compound (50 mg/ml) dissolved in water with polysorbate 80 (Tween 80) (100 mg/kg), the effects of amiodarone in ethanol (5 mg/kg) and polysorbate 80 (10 mg/kg) were studied individually, and in combination in anesthetized dogs. Commercial intravenous amiodarone and polysorbate 80 caused at least a 60% drop in mean blood pressure and left ventricular maximum dP/dt for at least 30 min, whereas amiodarone in ethanol did not. The drop in blood pressure was not principally due to peripheral vasodilation. Therefore, in dogs the diluent polysorbate 80 is the major cause of severe hypotension resulting from commercial intravenous amiodarone. These studies show that commercial intravenous amiodarone produces results different in dogs than has been previously reported in humans. Therefore: (a) canine models for studying the antiarrhythmic actions of commercial intravenous amiodarone would produce results complicated by severe hypotension; and (b) polysorbate 80 is not an inert substance, but is a potent cardiac depressant.