Effects of sotalol on ambulatory electrocardiography in volunteers.

The effects of sotalol dosing, 160, 240, and 320 mg/day, for 10 days in seven healthy volunteers were studied. Twenty-four-hour ECG was recorded continuously under placebo and on days 2, 4, 6, 8, 10, 11, 13, and 14. Sotalol at the three doses significantly lowered mean heart rate, reducing mean diurnal heart rate significantly between noon and 6:00 PM and decreasing mean nocturnal heart rate between midnight and 6:00 AM at 320 mg/day. Although there was no change in plasma sotalol between days 4 and 10, at high doses a significant decrease in bradycardiac effect occurred. PR intervals and QTc intervals were lengthened at all doses during the daytime. At the highest dose, the PR interval was lengthened during the nighttime.