Sotalol: Current Status and Expanding Indications

Molecular determinants of pro-arrhythmia proclivity of d- and l-sotalol via a multi-scale modeling pipeline

Drug isomers may differ in their proarrhythmia risk. An interesting example is the drug sotalol, an antiarrhythmic drug comprising d- and l- enantiomers that both block the hERG cardiac potassium channel and confer differing degrees of proarrhythmic risk. We developed a multi-scale in silico pipeline focusing on hERG channel – drug interactions and used it to probe and predict the mechanisms of pro-arrhythmia risks of the two enantiomers of sotalol. Molecular dynamics (MD) simulations predicted comparable hERG channel binding affinities for d- and l-sotalol, which were validated with electrophysiology experiments. MD derived thermodynamic and kinetic parameters were used to build multi-scale functional computational models of cardiac electrophysiology at the cell and tissue scales. Functional models were used to predict inactivated state binding affinities to recapitulate electrocardiogram (ECG) QT interval prolongation observed in clinical data. Our study demonstrates how modeling and simulation can be applied to predict drug effects from the atom to the rhythm for dl-sotalol and also increased proarrhythmia proclivity of d- vs. l-sotalol when accounting for stereospecific beta-adrenergic receptor blocking.

Does Sotalol Still Have a Role in the Management of Arrhythmias?

Despite proven effectiveness in treating tachyarrhythmias, sotalol is proarrhythmic and can cause torsades de pointes. Given the emergence of studies that show no benefit from rhythm control strategies in managing atrial fibrillation, as well as the introduction of nonpharmacological approaches to treating arrhythmias, we felt it necessary to ascertain if there was any role for sotalol given its side effects. Review of the literature regarding sotalol use in the prevention and treatment of supraventricular and ventricular tachyarrhythmias seems to show that more effective and safer agents and nonpharmacological alternatives are currently available. However, sotalol still seems to be useful in preventing supraventricular tachyarrhythmias postcardiac surgery and in reverting hemodynamically stable sustained ventricular tachycardias in the setting of coronary artery disease. Its role in the prevention of tachyarrhythmias in the setting of arrhythmogenic right ventricular cardiomyopathy requires further investigation.

Analysis of 24-h Rhythm in Ventricular Repolarization Identifies QT Diurnality As a Novel Clinical Parameter Associated with Previous Ventricular Arrhythmias in Heart Failure Patients

Introduction: Cardiac repolarization abnormalities are among the major causes of ventricular arrhythmias and sudden cardiac death. In humans, cardiac repolarization duration has a 24-h rhythm. Animal studies show that this rhythm is regulated by 24-h rhythms in ion channel function and that disruption of this rhythm leads to ventricular arrhythmias. We hypothesized that 24-h rhythms in QT duration can be used as a predictor for sudden cardiac death and are associated with ventricular arrhythmias. Secondly, we assessed a possible mechanistic explanation by studying the putative role of hERG channel dysfunction.

Materials and Methods: In 2 retrospective studies, measures of the 24-h variation in the QT and QTc intervals (QT and QTc diurnality, QTd and QTcd, respectively) have been derived from Holter analyses and compared between groups: 1) 39 post-infarct patients with systolic heart failure (CHF: EF < 35%), of which 14 with, and 25 without a history of ventricular arrhythmias and 2) five patients with proven (LQTS2) and 16 with potential (Sotalol-induced) hERG channel dysfunction vs. 22 controls.

Results: QTd was two-fold higher in CHF patients with a history of ventricular arrhythmias (38 ± 15 ms) compared to CHF patients without VT (16 ± 9 ms, p = 0.001). QTd was significantly increased in LQT2 patients (43 ± 24 ms) or those treated with Sotalol (30 ± 10 ms) compared to controls (21 ± 8 ms, p < 0.05 for both).

Discussion: QT diurnality presents a novel clinical parameter of repolarization that can be derived from Holter registrations and may be useful for identification of patients at risk for ventricular arrhythmias.

Antiarrhythmic and Proarrhythmic Properties of QT-Prolonging Antianginal Drugs

In recent years there has been a major reorientation of drug therapy for cardiac arrhythmias, its changing role, and above all, a radical change in the class of arrhythmia drugs because of their impact on mortality. The decline in the use of sodium-channel blockers has led to an expanding use of β-blockers and simple or complex class III agents for controlling cardiac arrhythmias. Success with these agents in the context of their side effects has spurred the development of compounds with simpler ion-channel blocking properties that have less complex adverse reactions. The resulting so-called pure class III agents, such as dofetilide or ibutilide, were found to have antifibrillatory effects in atrial fibrillation and flutter and in ventricular tachyarrhythmias. Such agents are effective and have diversity, but they have come into therapeutics with a price: the sometimes-fatal torsades de pointes. The drug amiodarone, a complex compound that was synthesized as an antianginal agent, has been an exception in this regard. Its therapeutic use is associated with a negligibly low incidence of torsades de pointes, even though the drug produces significant bradycardia and QT lengthening to 500 to 700 msec. Recent electrophysiologic studies suggest that this paradox is likely due to the differential block of ion channels in endocardium, epicardium, midmyocardial (M) cells, and Purkinje fibers in the ventricular myocardium. There is also clinical evidence suggesting that amiodarone reduces the “torsadogenic” effects of pure class III agents. Ranolazine was also synthesized for the development of antianginal properties that stem from a partial inhibition of fatty acid oxidation; it too has been found to have electrophysioloigic properties. These are somewhat similar to those of amiodarone on ion channels in endocardium, epicardium, M cells, and Purkinje fibers in the ventricular myocardium, but the drug does not prolong the QT interval to the same extent as amiodarone does. Thus, the drug produces modest increases in repolarization as judged by its effects on the action potential duration (APD) without the potential for the development of torsades de pointes. By virtue of its suppressant action on early afterdepolarizations and triggered activity in Purkinje fibers and M cells, the drug appears to have a powerful potential for reducing the torsadogenic proclivity of conventional class III antiarrhythmic compounds. The rationale for the therapeutic niche for amiodarone, and especially in the case of ranolazine, in the prevention of drug-induced torsades de pointes is discussed.

Chronic Suppression of Ventricular Tachyarrhythmias in Patients with ICDs

In this review, we examine the data evaluating the role of adjuvant therapy with antiarrthymic drugs (AADs) in chronic suppression of ventricular tachyarrhythmias in the patient with an ICD. It must be noted that all uses of AADs for this indication represent "off-label" prescription. No AAD is approved by the Food and Drug Administration (FDA) specifically as a therapy to reduce ICD shocks.

Amiodarone versus sotalol for atrial fibrillation

BACKGROUND

The optimal pharmacologic means to restore and maintain sinus rhythm in patients with atrial fibrillation remains controversial.

METHODS

In this double-blind, placebo-controlled trial, we randomly assigned 665 patients who were receiving anticoagulants and had persistent atrial fibrillation to receive amiodarone (267 patients), sotalol (261 patients), or placebo (137 patients) and monitored them for 1 to 4.5 years. The primary end point was the time to recurrence of atrial fibrillation beginning on day 28, determined by means of weekly transtelephonic monitoring.

RESULTS

Spontaneous conversion occurred in 27.1 percent of the amiodarone group, 24.2 percent of the sotalol group, and 0.8 percent of the placebo group, and direct-current cardioversion failed in 27.7 percent, 26.5 percent, and 32.1 percent, respectively. The median times to a recurrence of atrial fibrillation were 487 days in the amiodarone group, 74 days in the sotalol group, and 6 days in the placebo group according to intention to treat and 809, 209, and 13 days, respectively, according to treatment received. Amiodarone was superior to sotalol (P<0.001) and to placebo (P<0.001), and sotalol was superior to placebo (P<0.001). In patients with ischemic heart disease, the median time to a recurrence of atrial fibrillation was 569 days with amiodarone therapy and 428 days with sotalol therapy (P=0.53). Restoration and maintenance of sinus rhythm significantly improved the quality of life and exercise capacity. There were no significant differences in major adverse events among the three groups.

CONCLUSIONS

Amiodarone and sotalol are equally efficacious in converting atrial fibrillation to sinus rhythm. Amiodarone is superior for maintaining sinus rhythm, but both drugs have similar efficacy in patients with ischemic heart disease. Sustained sinus rhythm is associated with an improved quality of life and improved exercise performance.

Biopharmaceutical characterization of sotalol-containing oral immediate release drug products

The objective of this study was replacing an in vivo bioequivalence study by generating suitable in vitro data in order to get generic marketing authorisation. Solubility and permeability of sotalol hydrochloride were determined thereby achieving classification of this compound according to the biopharmaceutical classification system. In addition comparative investigation of in vitro dissolution properties of different Sota-saar formulations and the reference product provided satisfying justification to waive in vivo bioavailability (BA)/bioequivalence (BE) studies. The investigations on solubility were performed considering the highest dose strength in aqueous media (250 ml) with pH conditions between pH 1.0 and 7.5. Permeability was studied using the human colorectal carcinoma cell line Caco-2. In vitro as well as in vivo data suggest high permeability of the drug compound through the intestinal membrane. Thus, evaluation of solubility and permeability allow sotalol hydrochloride to be classified as biopharmaceutics classification system class I drug. In vitro dissolution profiles demonstrate comparable rapid dissolution (more than 85% in 15 min) for test and reference products. Summarizing, relevant prerequisites are fulfilled to waive BA/BE studies.

Significance and control of cardiac arrhythmias in patients with congestive cardiac failure

A wide spectrum of ventricular and supraventricular tachyarrhythmias occurs in the setting of congestive cardiac failure. However, the two most clinically significant are atrial fibrillation and ventricular tachycardia and fibrillation. In the past there has been much emphasis on premature ventricular contractions and more recently, on nonsustained ventricular tachycardia. For the most part, these arrhythmias are asymptomatic in heart failure. They are markers of sudden arrhythmic death but their suppression by antiarrhythmic drugs have not resulted in a reduction of total mortality. Two approaches have been used to this end. The first is the use of beta-adrenergic blocking drugs and antiarrhythmic agents such as amiodarone. Beta-blockers have been shown to significantly reduce sudden death as well as total mortality, while the effects of amiodarone have been less decisive. The prospective role of the implantable cardioverter defibrillator (ICD) is undergoing critical evaluation in patients with cardiac failure at high risk for sudden death. The elective role of the ICD is well established as first-line therapy in patients with heart failure resuscitated from sudden death and in those with sustained ventricular tachycardia in conjunction with conventional therapies for cardiac decompensation. The prevalence of atrial fibrillation rises as a function of severity of cardiac failure, but it is also in known that persistent atrial fibrillation with an uncontrolled ventricular response may induce heart failure. Controlled ventricular response may prevent congestive heart failure and improve left ventricular function. The two most common causes of atrial fibrillation in cardiac failure in Europe and America are ischemic heart disease and hypertension, while mitral valve disease remains the prevalent cause elsewhere. The choice of antiarrhythmic drugs for maintaining sinus rhythm is critical in the prevention of heart failure aggravation and proarrhythmic reactions of antiarrhythmic drugs. Amiodarone and dofetilide are most widely used in this context.

Antiarrhythmic agents for atrial fibrillation: focus on prolonging atrial repolarization

Atrial fibrillation (AF) has been the subject of considerable attention and intensive clinical research in recent years. Current opinion among physicians on the management of AF favors the restoration and maintenance of normal sinus rhythm. This has several potential benefits, including the alleviation of arrhythmia-associated symptoms, hemodynamic improvements, and possibly a reduced risk of thromboembolic events. After normal sinus rhythm has been restored, antiarrhythmic therapy is necessary to reduce the frequency of AF recurrence. In the selection of an antiarrhythmic agent, both efficacy and safety should be taken into consideration. Many antiarrhythmic agents have the capacity to provoke proarrhythmia, which may result in an increase in mortality. This is of particular concern with sodium-channel blockers in the context of patients with structural heart disease. Flecainide and propafenone are well tolerated and effective in maintaining sinus rhythm in patients without significant cardiac disease but with AF. Recent interest has focused on the use of class III antiarrhythmic agents, such as amiodarone, sotalol, dofetilide (recently approved), ibutilide (approved for chemical conversion of AF and atrial flutter), and azimilide (still to be approved) in patients with AF and structural heart disease. To date, amiodarone and sotalol still hold the greatest interest, and although controlled clinical trials with these agents have been few, a number are in progress and some have been recently completed. These agents are effective in maintaining normal sinus rhythm in patients with paroxysmal and persistent AF and are associated with a low incidence of proarrhythmia when used appropriately. Because of the relative paucity of placebo-controlled trials of antiarrhythmic agents in patients with AF, experience until recently has tended to dictate treatment decisions. Increasingly, selection of drug therapy is being based on a careful and individualized benefit-risk evaluation by means of controlled clinical trials, an approach that is likely to dominate the overall approach to the control of atrial fibrillation in the largest numbers of cases of the arrhythmia. Pharmacologic therapy is likely to be dominated by compounds that exert their predominant effect by prolonging atrial repolarization.

Recurrent Torsades de Pointes After Sotalol Therapy for Symptomatic Paroxysmal Atrial Fibrillation in a Patient with End-Stage Renal Disease

BACKGROUND: In recent years there has been ain increase in the use of class III antiarrhythmic drugs such as sotalol, amiodarone, and the so-called pure class III compound for the control of cardiac arrhythmias. It appears there has been a corresponding increase in the frequency of torsades de pointes (TdP). METHODS AND RESULTS: The case reported here, a patient on daily renal dialysis for end-stage renal disease, has important implications for class III agents, which are excreted largely by the kidneys. A relatively low dose of sotalol administered for the prevention of recurrences of atrial fabrillation, with a fast ventricular response producing angina, led to modest increases in the QT interval and moderate bradycardia. This culminated in the development of TdP, which deteriorated into ventricular fibrillation, from which the patient could be resuscitated with considerable difficulty. Dialysis after the occurrence of TdP led to further and striking prolongation of the QT interval associated with numerous episodes of TdP for several days before control was achieved. The atrial fibrillation and recurrences of TdP were eventually controlled with oral amiodarone. CONCLUSIONS: This case emphasizes that in the absence of significant renal function, use of sotalol may not be safe because drug accumulation may not be controlled adequately with renal dialysis. In view of this, in patients with end-stage renal disease, the use of sotalol for arrhythmia control appears contraindicated and alternative agents, the excretion of which does not occur by the renal route, should be used.