Sotalol is a methane sulfonanilide beta adrenergic antagonist used to treat life-threatening ventricular arrhythmias and to maintain sinus rhythm in atrial fibrillation or flutter. After being taken orally, it is absorbed into the blood through the GI tract and inhibits the beta 1 adrenergic receptor and the potassium voltage gated channel subfamily H member 2 protein on the cell membranes of cardiomyocytes. The beta 1 adrenergic receptor is responsible for Gs signalling and the production of cyclic adenosine monophosphate (cAMP) which activates the L-type calcium channel. The L-type calcium channel is responsible for the influx of calcium from extracellular environment into the cytosol of cardiomyocytes which activates ryanodine receptors to release calcium from the sarcoplasmic reticulum. Calcium is important for the contraction of heart muscle for myosin to and actin to power-stroke so the slower influx of calcium slows down the contractions of the heart lowering the heart rate. Sotalol is a competitive inhibitor of the rapid potassium channel. This inhibition lengthens the duration of action potentials and the refractory period in the atria and ventricles. The inhibition of rapid potassium channels is increases as heart rate decreases, which is why adverse effects like torsades de points is more likely to be seen at lower heart rates. The inhibition of potassium voltage gated channel subfamily H member 2 protein inhibits the efflux of potassium out of the cell during the repolarization phase of an action potential. This lengthens the QT interval of the heartbeat as well as prolonging the repolarization phase of action potentials. This regulates the heart rate and slows down any rapid heartrates. The action of sotalol on beta adrenergic receptors lengthens the sinus node cycle, conduction time through the atrioventricular node, refractory period, and duration of action potentials. Sotalol can be found under the brand names Betapace, Sorine, and Sotylize. Some side effects of using this drug may include feeling dizzy or sick, feeling tired, having diarrhoea or a headache.

Sotalol Pathway (New) References