Pharmacology, pharmacodynamics and pharmacokinetics of sotalol

Sotalol is a nonselective, water-soluble beta-adrenoceptor antagonist with no membrane-stabilizing activity or intrinsic sympathomimetic activity. Sotalol is, essentially, completely absorbed and is not metabolized. Consequently, bioavailability is close to 100%. Age and food have slight but unimportant effects on bioavailability. Cmax of sotalol is 2 to 3 hours with a t1/2 between 7 and 15 hours. Excretion of sotalol is primarily through the kidneys, with no metabolism by liver and no first-pass effect. Therefore, sotalol plasma levels and half-life are directly related to creatinine clearance and glomerular filtration rate. Appropriate dose adjustments must be made for patients with impaired renal function or increased renal blood flow, as in pregnancy. The beta-adrenoceptor antagonistic effects of sotalol are directly related to plasma levels, which, in turn, are directly related to dose. However, the beta-adrenoceptor antagonism t1/2 is longer than the sotalol plasma t1/2. As a consequence of its ability to prolong the action potential duration, sotalol also increases cardiac contractility in isolated ventricular, but not atrial, preparations by 20 to 40%. This positive inotropic effect is not blocked by beta or alpha blockade or reserpine pretreatment and seems to be related to sotalol's effects on cardiac ionic currents. Like the effects of sotalol on action potential duration, the positive inotropic effects are inversely proportional to rate. The hemodynamics of sotalol indicate a relative lack of direct cardiac depressant activity in both animals and humans. The typical hemodynamic effects of sotalol in normotensive humans, even with depressed myocardial function, are a reduction in heart rate with little or no change in blood pressure, a reduction in cardiac output with no change in stroke volume, and little or no change in pulmonary wedge pressure and left ventricular end-diastolic pressure or volume, and little or no change in ejection fraction either at rest or during exercise.