SOTALOL

SOTALOL- sotalol tablet
MUTUAL PHARMACEUTICAL

Rx only

To minimize the risk of induced arrhythmia, patients initiated or re-initiated on sotalol hydrochloride tablets (AF) should be placed for a minimum of three days (on their maintenance dose) in a facility that can provide cardiac resuscitation, continuous electrocardiographic monitoring and calculations of creatinine clearance. For detailed instructions regarding dose selection and special cautions for people with renal impairment, see DOSAGE AND ADMINISTRATION. Sotalol is also indicated for the treatment of documented life-threatening ventricular arrhythmias and is marketed under the brand name BETAPACE®. BETAPACE® however, should not be substituted for sotalol hydrochloride tablets (AF) because of significant differences in labeling (i.e. patient package insert, dosing administration and safety information).

DESCRIPTION

Sotalol hydrochloride, is an antiarrhythmic drug with Class II (beta-adrenoreceptor blocking) and Class III (cardiac action potential duration prolongation) properties. It is supplied as a white, capsule-shaped tablet for oral administration. Sotalol hydrochloride is a white, crystalline solid with a molecular weight of 308.8. It is hydrophilic, soluble in water, propylene glycol and ethanol, but is only slightly soluble in chloroform. Chemically, sotalol hydrochloride tablets (AF) is d,l-N-[4-[l-hydroxy-2-[(l-methylethyl) amino]ethyl]phenyl]methane-sulfonamide monohydrochloride. The molecular formula is C12 H20 N2 O3 S•HCl and is represented by the following structural formula:

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Each tablet contains 80 mg, 120 mg, or 160 mg of sotalol hydrochloride. In addition, each tablet contains the following inactive ingredients: anhydrous lactose, colloidal silicon dioxide, corn starch, magnesium stearate, microcrystalline cellulose, pregelatinized starch, sodium starch glycolate, stearic acid.

CLINICAL PHARMACOLOGY

Mechanism of Action

Sotalol hydrochloride has both beta-adrenoreceptor blocking (Vaughan Williams Class II) and cardiac action potential duration prolongation (Vaughan Williams Class III) antiarrhythmic properties. Sotalol hydrochloride tablets (AF) is a racemic mixture of d- and l-sotalol. Both isomers have similar Class III antiarrhythmic effects, while the l-isomer is responsible for virtually all of the beta-blocking activity. The beta-blocking effect of sotalol is non-cardioselective, half maximal at about 80 mg/day and maximal at doses between 320 and 640 mg/day. Sotalol does not have partial agonist or membrane stabilizing activity. Although significant beta-blockade occurs at oral doses as low as 25 mg, significant Class III effects are seen only at daily doses of 160 mg and above.

In children, a Class III electrophysiological effect can be seen at daily doses of 210 mg/m2 body surface area (BSA). A reduction of the resting heart rate due to the beta-blocking effect of sotalol is observed at daily doses ≥ 90 mg/m2 in children.

Electrophysiology

Sotalol hydrochloride prolongs the plateau phase of the cardiac action potential in the isolated myocyte, as well as in isolated tissue preparations of ventricular or atrial muscle (Class III activity). In intact animals it slows heart rate, decreases AV nodal conduction and increases the refractory periods of atrial and ventricular muscle and conduction tissue.

In man, the Class II (beta-blockade) electrophysiological effects of sotalol are manifested by increased sinus cycle length (slowed heart rate), decreased AV nodal conduction and increased AV nodal refractoriness. The Class III electrophysiological effects in man include prolongation of the atrial and ventricular monophasic action potentials, and effective refractory period prolongation of atrial muscle, ventricular muscle, and atrio-ventricular accessory pathways (where present) in both the anterograde and retrograde directions. With oral doses of 160 to 640 mg/day, the surface ECG shows dose-related mean increases of 40-100 msec in QT and 10-40 msec in QTc . In a study of patients with atrial fibrillation (AFIB)/flutter (AFIB/AFL) receiving three different oral doses of sotalol given q12h (or q24h in patients with a reduced creatinine clearance), mean increases in QT intervals measured from 12-lead ECGs of 25 msec, 40 msec and 54 msec were found in the 80 mg, 120 mg and 160 mg dose groups, respectively. (See WARNINGS for description of relationship between QTc and torsade de pointes type arrhythmias.) No significant alteration in QRS interval is observed.

In a small study (n=25) of patients with implanted defibrillators treated concurrently with sotalol the average defibrillatory threshold was 6 joules (range 2-15 joules) compared to a mean of 16 joules for a non-randomized comparative group primarily receiving amiodarone.

In a dose-response trial comparing three dose levels of sotalol hydrochloride tablets (AF), 80 mg, 120 mg, and 160 mg with placebo given q12h (or q24h in patients with a reduced renal creatinine clearance) for the prevention of recurrence of symptomatic atrial fibrillation (AFIB)/flutter (AFL), the mean ventricular rate during recurrence of AFIB/AFL was 125, 107, 110 and 99 beats/min in the placebo, 80 mg, 120 mg and 160 mg dose groups, respectively (p < 0.017 for each sotalol dose group versus placebo). In another placebo controlled trial in which sotalol hydrochloride tablets (AF) was titrated to a dose between 160 and 320 mg/day in patients with chronic AFIB, the mean ventricular rate during recurrence of AFIB was 107 and 84 beats/min in the placebo and sotalol hydrochloride tablets (AF) groups, respectively (p< 0.001).

Twenty-five children in an unblended, multicenter trial with supraventricular (SVT) and/or ventricular (VT) tachyarrhythmias, aged between 3 days and 12 years (mostly neonates and infants), received an ascending titration regimen with daily doses of 30, 90 and 210 mg/m2 with dosing every 8 hours for a total of 9 doses. During steady-state, the respective average increases above baseline of the QTC interval, in msec (%), were 2 (+1%), 14 (+4%) and 29 (+7%) msec at the 3 dose levels. The respective mean maximum increases above baseline of the QTC interval, in msec (%) were 23 (+6%), 36 (+9%) and 55 (+14%) msec at the 3 dose levels. The steady-state percent increases in the RR interval were 3, 9 and 12%. The smallest children (BSA < 0.33 m2) showed a tendency for larger Class III effects (ΔQTC ) and an increased frequency of prolongations of the QTC interval as compared with the larger children (BSA ≥ 0.33 m2). The beta-blocking effects also tended to be greater in the smaller children (BSA < 0.33m2). Both the Class III and beta-blocking effects of sotalol were linearly related with the plasma concentrations.

Hemodynamics

In a study of systemic hemodynamic function measured invasively in 12 patients with a mean LV ejection fraction of 37% and ventricular tachycardia (9 sustained and 3 non-sustained), a median dose of 160 mg twice daily of sotalol produced a 28% reduction in heart rate and a 24% decrease in cardiac index at 2 hours post dosing at steady-state. Concurrently, systemic vascular resistance and stroke volume showed non-significant increases of 25% and 8%, respectively. Pulmonary capillary wedge pressure increased significantly from 6.4 mmHg to 11.8 mmHg in the 11 patients who completed the study. One patient was discontinued because of worsening congestive heart failure. Mean arterial pressure, mean pulmonary artery pressure and stroke work index did not significantly change. Exercise and isoproterenol induced tachycardia are antagonized by sotalol, and total peripheral resistance increases by a small amount.

In hypertensive patients, sotalol produces significant reductions in both systolic and diastolic blood pressures. Although sotalol is usually well-tolerated hemodynamically, caution should be exercised in patients with marginal cardiac compensation as deterioration in cardiac performance may occur. (See WARNINGS: Congestive Heart Failure.).

Clinical Studies

Prolongation of Time to Recurrence of Symptomatic Atrial Fibrillation/Flutter

Sotalol hydrochloride tablets (AF) has been studied in patients with symptomatic AFIB/AFL in two principal studies, one in patients with primarily paroxysmal AFIB/AFL, the other in patients with primarily chronic AFIB.

In one study, a U.S. multicenter, randomized, placebo-controlled, double-blind, dose-response trial of patients with symptomatic primarily paroxysmal AFIB/AFL, three fixed dose levels of sotalol hydrochloride tablets (AF) (80 mg, 120 mg and 160 mg) twice daily and placebo were compared in 253 patients. In patients with reduced creatinine clearance (40 to 60 mL/min) the same doses were given once daily. Patients were not randomized for the following reasons: QT > 450 msec; creatinine clearance < 40 mL/min; intolerance to beta-blockers; bradycardia-tachycardia syndrome in the absence of an implanted pacemaker; AFIB/AFL was asymptomatic or was associated with syncope, embolic CVA or TIA; acute myocardial infarction within the previous 2 months; congestive heart failure; bronchial asthma or other contraindications to beta-blocker therapy; receiving potassium losing diuretics without potassium replacement or without concurrent use of ACE-inhibitors; uncorrected hypokalemia (serum potassium < 3.5 meq/L) or hypomagnesemia (serum magnesium < 1.5 meq/L); received chronic oral amiodarone therapy for > 1 month within previous 12 weeks; congenital or acquired long QT syndromes; history of torsade de pointes with other antiarrhythmic agents which increase the duration of ventricular repolarization; sinus rate < 50 bpm during waking hours; unstable angina pectoris; receiving treatment with other drugs that prolong the QT interval; and AFIB/AFL associated with the Wolff-Parkinson-White (WPW) syndrome. If the QT interval increased to ≥ 520 msec (or JT ≥ 430 msec if QRS > 100 msec) the drug was discontinued. The patient population in this trial was 64% male, and the mean age was 62 years. No structural heart disease was present in 43% of the patients. Doses were administered once daily in 20% of the patients because of reduced creatinine clearance.

Sotalol hydrochloride tablets (AF) were shown to prolong the time to the first symptomatic, ECG-documented recurrence of AFIB/AFL, as well as to reduce the risk of such recurrence at both 6 and 12 months. The 120 mg dose was more effective than 80 mg, but 160 mg did not appear to have an added benefit. Note that these doses were given twice or once daily, depending on renal function. The results are shown in Figure 1 and Tables 1 and 2.

Figure 1Study 1 — Time to First ECG-Documented Recurrence of Symptomatic AFIB/AFL Since Randomization

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Table 1 Study 1 – Patient Status at 12 Months
Sotalol Hydrochloride Tablets (AF) Dose
Placebo 80 mg 120 mg 160 mg
Please note that columns do not add up to 100% due to discontinuations (D/C) for “other” reasons.
*
Symptomatic AFIB/AFL
Efficacy endpoint of Study 1; study treatment stopped
Randomized 69 59 63 62
On treatment in NSR at 12 months without recurrence * 23% 22% 29% 23%
Recurrence *, 67% 58% 49% 42%
D/C for AEs 6% 12% 18% 29%
Table 2 Study 1 – Median Time to Recurrence of Symptomatic
Sotalol Hydrochloride Tablets (AF) Dose
Placebo 80 mg 120 mg 160 mg
AFIB/AFL and Relative Risk (vs. Placebo) at 12 Months
p-value vs placebo p=0.325 p=0.018 p=0.029
Relative Risk (RR) to placebo 0.81 0.59 0.59
Median time to recurrence (days) 27 106 229 175

Discontinuation because of adverse events was dose related.

In a second multicenter, randomized, placebo-controlled, double-blind study of 6 months duration in 232 patients with chronic AFIB, sotalol hydrochloride tablets (AF) was titrated over a dose range from 80 mg/day to 320 mg/day. The patient population of this trial was 70% male with a mean age of 65 years. Structural heart disease was present in 49% of the patients. All patients had chronic AFIB for > 2 weeks but < 1 year at entry with a mean duration of 4.1 months. Patients were excluded if they had significant electrolyte imbalance, QTc > 460 msec, QRS > 140 msec, any degree of AV block or functioning pacemaker, uncompensated cardiac failure, asthma, significant renal disease (estimated creatinine clearance < 50 mL/min), heart rate < 50 bpm, myocardial infarction or open heart surgery in past 2 months, unstable angina, infective endocarditis, active pericarditis or myocarditis, ≥ 3 DC cardioversions in the past, medications that prolonged QT interval, and previous amiodarone treatment. After successful cardioversion patients were randomized to receive placebo (n=114) or sotalol hydrochloride tablets (AF) (n=118) at a starting dose of 80 mg twice daily. If the initial dose was not tolerated it was decreased to 80 mg once daily, but if it was tolerated it was increased to 160 mg twice daily. During the maintenance period 67% of treated patients received a dose of 160 mg twice daily, and the remainder received doses of 80 mg once daily (17%) and 80 mg twice daily (16%).

Figure 2 and Tables 3 and 4 show the results of the trial. There was a longer time to ECG-documented recurrence of AFIB and a reduced risk of recurrence at 6 months compared to placebo.

Figure 2Study 2 — Time to First ECG-Documented Recurrence of Symptomatic

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Table 3
Sotalol Hydrochloride Tablets (AF) Placebo
Study 2 — Patient Status at 6 Months
*
Symptomatic or asymptomatic AFIB/AFL
Efficacy endpoint of Study 2; study treatment stopped
Randomized 118 114
On treatment in NSR at 6 months without recurrence * 45% 29%
Recurrence *, 49% 67%
D/C for AEs 6% 3%
Death 1%
Table 4 Study 2 – Median Time to Recurrence of Symptomatic AFIB/AFL/Death and Relative Risk (vs. Placebo) at 6 Months
Sotalol Hydrochloride Tablets (AF) Placebo
p-value vs placebo p=0.002
Relative Risk (RR) to placebo 0.55
Median time to recurrence (days) > 180 44

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