|Systematic (IUPAC) name|
|Metabolism||Not metabolized|
Lactic (In lactating females)
|Mol. mass||272.3624 g/mol|
|(what is this?)|
Sotalol is a drug used in individuals with rhythm disturbances (cardiac arrhythmias) of the heart, and to treat hypertension in some individuals. It is a non-selective competitive β-adrenergic receptor blocker that also exhibits Class III antiarrhythmic properties by its inhibition of potassium channels. Because of this dual action, Sotalol prolongs both the PR interval and the QT interval. Originally discovered around 1960, sotalol became widely used first as a β-blocker in the 1980s, and its function as an antiarrhythmic drug was discovered soon after. Due to the dual action of sotalol, it is often used preferentially to other β-blockers as treatment for both ventricular fibrillation and ventricular tachycardia.
It has also been suggested that it be used in the prevention of atrial fibrillation.
Ventricular Fibrillation and Tachycardia
Ventricular fibrillation is an uncontrolled and asynchronous series of contractions of the ventricles resulting in poor cardiac output. It is often associated with factors that affect the electrical signal for contraction and trigger a premature contraction before complete relaxation. Ventricular tachycardia is closely associated with ventricular fibrillation and is an abnormally high rate of contraction from the ventricles often resulting from increased intracellular calcium levels. This increase in cytosolic calcium leads to an increase in calcium release from the sarcoplasmic reticulum, which increases rate of contraction by providing more calcium for interaction with force-generating filaments in the muscle cell for a prolonged period of time.
Mechanisms of Action
Sotalol non-selectively binds to both β1- and β2-adrenergic receptors preventing activation of the receptors by their stimulatory ligand1. Without the binding of this ligand to the receptor, the G-protein complex associated with the receptor cannot activate production of cyclic AMP, which is responsible for turning on calcium inflow channels. A decrease in activation of calcium channels will therefore result in a decrease in intracellular calcium. In cardiac cells, calcium is important in generating electrical signals for contraction, as well as generating force for contraction. In consideration of these important properties of calcium, two conclusions can be drawn. Firstly, with less calcium in the cell, there is a decrease in electrical signals for contraction, thus allowing time for the heart’s natural pacemaker to rectify arrhythmic contractions3. Secondly, lower calcium means a decrease in strength and rate of the contractions, which can be helpful in treatment of abnormally high heart rates in patients with tachycardia3.
Type III Antiarrhythmic Action
Sotalol also acts on potassium channels and causes a delay in relaxation of the ventricles2. By blocking these potassium channels, sotalol inhibits efflux of K+ ions, which results in an increase in the time before another electrical signal can be generated in ventricular myocytes8. This increase in the period before a new signal for contraction is generated, helps to correct arrhythmias by reducing the potential for premature or abnormal contraction of the ventricles but also prolongs the frequency of ventricular contraction to help treat tachycardia.
- Bertrix, Lucien et al. Protection against ventricular and atrial fibrillation by sotalol. Cardiovascular Research 1986; 20, 358-363.
- Edvardsson, N et al. Sotalol-induced delayed ventricular repolarization in man. European Heart Journal 1980; 1, 335-343
- Antonaccio M, Gomoll A. Pharmacologic basis of the antiarrhythmic and hemodynamic effects of sotalol. Am J Cardiol 1993; 72, 27A-37A
- Dorian P, Newman D. Effect of sotalol on ventricular fibrillation and defibrillation in humans. Am J Cardiol 1993; 72, 72A-79A
- Boriani G, Lubinski A, Capucci A, et al. (December 2001). "A multicentre, double-blind randomized crossover comparative study on the efficacy and safety of dofetilide vs sotalol in patients with inducible sustained ventricular tachycardia and ischaemic heart disease". Eur. Heart J. 22 (23): 2180–91. doi:10.1053/euhj.2001.2679. PMID 11913480.
- Singh BN, Singh SN, Reda DJ, et al. (May 2005). "Amiodarone versus sotalol for atrial fibrillation". N. Engl. J. Med. 352 (18): 1861–72. doi:10.1056/NEJMoa041705. PMID 15872201.
- Waldo A, Camm A, deRuyter H, Friedman P, MacNeil D, Pauls J, Pitt B, Pratt C, Schwartz P, Veltri E (1996). "Effect of d-sotalol on mortality in patients with left ventricular dysfunction after recent and remote myocardial infarction. The SWORD Investigators. Survival With Oral d-Sotalol". Lancet 348 (9019): 7–12. doi:10.1016/S0140-6736(96)02149-6. PMID 8691967.
- Patel A, Dunning J (April 2005). "Is Sotalol more effective than standard beta-blockers for the prophylaxis of atrial fibrillation during cardiac surgery". Interact Cardiovasc Thorac Surg 4 (2): 147–50. doi:10.1510/icvts.2004.102152. PMID 17670378.
- Wiggers, C. The mechanism and nature of ventricular fibrillation. The American Heart Journal 1940; 20, 399-412
- Priori, S et al. Mutations in the cardiac ryanodine receptor gene (hRyR2) underlie catecholaminergic polymorphic ventricular tachycardia. Circulation 2001; 103, 196-200
- Charnet, P et al. cAMP-dependent phosphorylation of the cardiac L-type Ca channel: A missing link? Biochimie 1995; 77, 957-962
- Kassotis, J et al. Beta receptor blockade potentiates the antiarryhthmic actions of d-sotalol on re-entrant ventricular tachycardia in a canine model of myocardial infarction. Journal of Cardiovascular Electrophysiology 2003; 14, 1233-1244