Observations on the Efficacy and Pharmacokinetics of Sotalol After Oral Administration

The effects of sotalol after oral administration were measured on the tachycardia induced by strenuous exercise in normal subjects. Plasma sotalol levels were also determined. The oral administration of sotalol (50, 100, 200 and 400 mg) to 6 subjects produced a progressive reduction in the tachycardia induced by severe exercise. This was similar to the effects of 25, 50, 100, 200, 400 and 800 mg given to different subjects. Each increase in sotalol dose produced a successively greater reduction in exercise tachycardia. This did not appear to be maximum even with 800 mg. Oral sotalol was rapidly absorbed and produced peak blood levels in 2 - 3 hours. The plasma levels of sotalol measured 2 hours after the oral administration of 25 to 800 mg showed never more than a six-fold variation between different subject. The half-life of sotalol in plasma was 12.7 +/- SE 1.6 hours. There was a significant correlation between the logarithm of the plasma sotalol concentration and the percentage reduction of exercise heart rate. It is concluded that the oral administration of sotalol either once or twice daily (depending on dose level) will provide satisfactory 24-hour blockade of beta-adrenoceptors.