A comparative study has been carried out on sotalol and propranolol with regard to their ability to block adrenergic β-receptors, their toxicity and their circulatory effects. Both agents blocked the hypotensive effects of isoprenaline in cats. The relationship between intravenously infused doses of propranolol and sotalol which were equally potent in their adrenergic β-receptor blocking properties was 1:3. In toxicity tests, propranolol was 6-20 times more toxic than sotalol under different experimental conditions and in different species of animals. Propranolol, infused intravenously into cats in a dose of 0.25 mg/kg/min, reduced the cardiac output, heart rate, blood pressure, and cardiac work. Sotalol in the same dosage reduced only the blood pressure and heart rate, while the cardiac output and cardiac work remained unchanged because of a compensatory increase in stroke volume. Propranolol, but not sotalol, reduced the contractile strength and increased the refractory period of electrically stimulated papillary muscle from the cat. Sotalol failed to inhibit ouabain-induced cardiac arrhythmias in dogs, an effect exerted by propranolol. These effects of propranolol, and also its local anesthetic properties, are probably not related to its adrenergic β-receptor blocking properties. As sotalol lacks direct effects it has an advantage over propranolol when specific adrenergic β-receptor blockades are required. © 1969.
