WARNINGS
Mortality
The National Heart, Lung, and Blood Institute's
Cardiac Arrhythmia Suppression Trial I (CAST I) was a long-term, multi-center,
double-blind study in patients with asymptomatic, non-life-threatening
ventricular arrhythmias, 1 to 103 weeks after acute myocardial infarction.
Patients in CAST I were randomized to receive placebo or individually optimized
doses of encainide, flecainide, or moricizine. The Cardiac Arrhythmia
Suppression Trial II (CAST II) was similar, except that the recruited patients
had had their index infarction 4 to 90 days before randomization, patients with
left ventricular ejection fractions greater than 40% were not admitted, and the
randomized regimens were limited to placebo and moricizine.
CAST I was discontinued after an average
time-on-treatment of 10 months, and CAST II was discontinued after an average
time-on-treatment of 18 months. As compared to placebo treatment, all three
active therapies were associated with increases in short-term (14-day)
mortality, and encainide and flecainide were associated with significant
increases in longer-term mortality as well. The longer-term mortality rate
associated with moricizine treatment could not be statistically distinguished
from that associated with placebo.
The applicability of these results to other populations
(e.g., those without recent myocardial infarction) and to other than Class I
antiarrhythmic agents is uncertain. Sotalol hydrochloride is devoid of Class I
effects, and in a large (n=1,456) controlled trial in patients with a recent
myocardial infarction, who did not necessarily have ventricular arrhythmias,
sotalol did not produce increased mortality at doses up to 320 mg/day (see Clinical
Studies). On the other hand, in the large postinfarction study using a
non-titrated initial dose of 320 mg once daily and in a second small randomized
trial in high-risk post-infarction patients treated with high doses (320 mg
BID), there have been suggestions of an excess of early sudden deaths.
Proarrhythmia
Like other antiarrhythmic agents, sotalol can provoke new
or worsened ventricular arrhythmias in some patients, including sustained
ventricular tachycardia or ventricular fibrillation, with potentially fatal
consequences. Because of its effect on cardiac repolarization (QTc interval
prolongation), Torsade de Pointes, a polymorphic ventricular tachycardia with
prolongation of the QT interval and a shifting electrical axis is the most
common form of proarrhythmia associated with sotalol, occurring in about 4% of
high risk (history of sustained VT/VF) patients. The risk of Torsade de Pointes
progressively increases with prolongation of the QT interval, and is worsened
also by reduction in heart rate and reduction in serum potassium (see Electrolyte
Disturbances).
Because of the variable temporal recurrence of
arrhythmias, it is not always possible to distinguish between a new or
aggravated arrhythmic event and the patient's underlying rhythm disorder.
(Note, however, that Torsade de Pointes is usually a drug-induced arrhythmia in
people with an initially normal QTc.) Thus, the incidence of drug-related
events cannot be precisely determined, so that the occurrence rates provided
must be considered approximations. Note also that drug-induced arrhythmias may
often not be identified, particularly if they occur long after starting the
drug, due to less frequent monitoring. It is clear from the NIH-sponsored CAST
(see WARNINGS, Mortality) that some antiarrhythmic drugs can
cause increased sudden death mortality, presumably due to new arrhythmias or
asystole, that do not appear early in treatment but that represent a sustained
increased risk.
Overall in clinical trials with sotalol, 4.3% of 3257
patients experienced a new or worsened ventricular arrhythmia. Of this 4.3%, there
was new or worsened sustained ventricular tachycardia in approximately 1% of
patients and Torsade de Pointes in 2.4%. Additionally, in approximately 1% of
patients, deaths were considered possibly drug-related; such cases, although
difficult to evaluate, may have been associated with proarrhythmic events. In
patients with a history of sustained ventricular tachycardia, the incidence of
Torsade de Pointes was 4% and worsened VT in about 1%; in patients with other,
less serious, ventricular arrhythmias and supraventricular arrhythmias, the
incidence of Torsade de Pointes was 1% and 1.4%, respectively.
Torsade de Pointes arrhythmias were dose related, as is
the prolongation of QT (QTc) interval, as shown in the table below.
Percent Incidence of Torsade de Pointes and Mean  QTc
Interval by Dose For Patients With Sustained VT/VF
Daily Dose (mg) |
Incidence of Torsade de Pointes |
Mean QTCa (msec) |
80 |
0 (69)b |
463 (17) |
160 |
0.5 (832) |
467 (181) |
320 |
1.6 (835) |
473 (344) |
480 |
4.4 (459) |
483 (234) |
640 |
3.7 (324) |
490 (185) |
> 640 |
5.8 (103) |
512 (62) |
a highest on-therapy value
b Number of patients assessed |
In addition to dose and presence of sustained VT, other
risk factors for Torsade de Pointes were gender (females had a higher
incidence), excessive prolongation of the QTc interval (see table below) and
history of cardiomegaly or congestive heart failure. Patients with sustained
ventricular tachycardia and a history of congestive heart failure appear to
have the highest risk for serious proarrhythmia (7%). Of the patients
experiencing Torsade de Pointes, approximately two-thirds spontaneously
reverted to their baseline rhythm. The others were either converted
electrically (D/C cardioversion or overdrive pacing) or treated with other
drugs (see OVERDOSAGE). It is not possible to determine whether some
sudden deaths represented episodes of Torsade de Pointes, but in some instances
sudden death did follow a documented episode of Torsade de Pointes. Although
sotalol therapy was discontinued in most patients experiencing Torsade de
Pointes, 17% were continued on a lower dose.
Nonetheless, sotalol should be used with particular
caution if the QTc is greater than 500 msec on-therapy and serious
consideration should be given to reducing the dose or discontinuing therapy
when the QTc exceeds 550 msec. Due to the multiple risk factors associated with
Torsade de Pointes, however, caution should be exercised regardless of the QTc interval.
The table below relates the incidence of Torsade de Pointes to on-therapy QTc and
change in QTc from baseline. It should be noted, however, that the highest
on-therapy QTc was in many cases the one obtained at the time of the Torsade de
Pointes event, so that the table overstates the predictive value of a high QTc.
Relationship Between QTc Interval Prolongation and Torsade
de Pointes
On-Therapy QTc Interval (msec) |
Incidence of Torsade de Pointes |
Change in QTc Interval From Baseline (msec) |
Incidence of Torsade de Pointes |
< 500 |
1.3% (1787) |
< 65 |
1.6% (1516) |
500-525 |
3.4% (236) |
65-80 |
3.2% (158) |
525-550 |
5.6% (125) |
80-100 |
4.1% (146) |
> 550 |
10.8% (157) |
100-130 |
5.2% (115) |
|
|
> 130 |
7.1% (99) |
( ) Number of patients assessed |
Proarrhythmic events must be anticipated not only on
initiating therapy, but with every upward dose adjustment. Proarrhythmic
events most often occur within 7 days of initiating therapy or of an increase
in dose; 75% of serious proarrhythmias (Torsade de Pointes and worsened VT)
occurred within 7 days of initiating sotalol therapy, while 60% of such events
occurred within 3 days of initiation or a dosage change. Initiating therapy at
80 mg BID with gradual upward dose titration and appropriate evaluations for
efficacy (e.g., PES or Holter) and safety (e.g., QT interval, heart rate and
electrolytes) prior to dose escalation, should reduce the risk of
proarrhythmia. Avoiding excessive accumulation of sotalol in patients with
diminished renal function, by appropriate dose reduction, should also reduce
the risk of proarrhythmia (see DOSAGE AND ADMINISTRATION).
Congestive Heart Failure
Sympathetic stimulation is necessary in supporting
circulatory function in congestive heart failure, and beta-blockade carries the
potential hazard of further depressing myocardial contractility and
precipitating more severe failure. In patients who have congestive heart
failure controlled by digitalis and/or diuretics, sotalol hydrochloride tablets
should be administered cautiously. Both digitalis and sotalol slow AV
conduction. As with all beta-blockers, caution is advised when initiating
therapy in patients with any evidence of left ventricular dysfunction. In
premarketing studies, new or worsened congestive heart failure (CHF) occurred
in 3.3% (n=3257) of patients and led to discontinuation in approximately 1% of
patients receiving sotalol. The incidence was higher in patients presenting
with sustained ventricular tachycardia/fibrillation (4.6%, n=1363), or a prior
history of heart failure (7.3%, n=696). Based on a lifetable analysis, the
one-year incidence of new or worsened CHF was 3% in patients without a prior
history and 10% in patients with a prior history of CHF. NYHA Classification
was also closely associated to the incidence of new or worsened heart failure
while receiving sotalol (1.8% in 1395 Class I patients, 4.9% in 1254 Class II
patients and 6.1% in 278 Class III or IV patients).
Electrolyte Disturbances
Sotalol should not be used in patients with hypokalemia
or hypomagnesemia prior to correction of imbalance, as these conditions can
exaggerate the degree of QT prolongation, and increase the potential for
Torsade de Pointes. Special attention should be given to electrolyte and
acid-base balance in patients experiencing severe or prolonged diarrhea or
patients receiving concomitant diuretic drugs.
Conduction Disturbances
Excessive prolongation of the QT interval ( > 550 msec)
can promote serious arrhythmias and should be avoided (see Proarrhythmia above).
Sinus bradycardia (heart rate less than 50 bpm) occurred in 13% of patients
receiving sotalol in clinical trials, and led to discontinuation in about 3% of
patients. Bradycardia itself increases the risk of Torsade de Pointes. Sinus
pause, sinus arrest and sinus node dysfunction occur in less than 1% of
patients. The incidence of 2nd- or 3rd-degree AV block is approximately 1%.
Recent Acute MI
Sotalol can be used safely and effectively in the
long-term treatment of life-threatening ventricular arrhythmias following a
myocardial infarction. However, experience in the use of sotalol to treat
cardiac arrhythmias in the early phase of recovery from acute MI is limited and
at least at high initial doses is not reassuring (see WARNINGS, Mortality).
In the first 2 weeks post-MI caution is advised and careful dose titration is
especially important, particularly in patients with markedly impaired
ventricular function.
The following warnings are related to the beta-blocking
activity of sotalol.
Abrupt Withdrawal
Hypersensitivity to catecholamines has been observed in
patients withdrawn from beta-blocker therapy. Occasional cases of exacerbation
of angina pectoris, arrhythmias and, in some cases, myocardial infarction have
been reported after abrupt discontinuation of beta-blocker therapy. Therefore,
it is prudent when discontinuing chronically administered sotalol hydrochloride
tablets, particularly in patients with ischemic heart disease, to carefully
monitor the patient and consider the temporary use of an alternate beta-blocker
if appropriate. If possible, the dosage of sotalol hydrochloride tablets should
be gradually reduced over a period of one to two weeks. If angina or acute
coronary insufficiency develops, appropriate therapy should be instituted
promptly. Patients should be warned against interruption or discontinuation of
therapy without the physician's advice. Because coronary artery disease is
common and may be unrecognized in patients receiving sotalol hydrochloride
tablets, abrupt discontinuation in patients with arrhythmias may unmask latent
coronary insufficiency.
Non-Allergic Bronchospasm (e.g., chronic
bronchitis and emphysema)
PATIENTS WITH BRONCHOSPASTIC DISEASES SHOULD IN
GENERAL NOT RECEIVE BETA-BLOCKERS. It is prudent, if sotalol hydrochloride
tablets are to be administered, to use the smallest effective dose, so that
inhibition of bronchodilation produced by endogenous or exogenous catecholamine
stimulation of beta 2 receptors may be minimized.
Anaphylaxis
While taking beta-blockers, patients with a history of
anaphylactic reaction to a variety of allergens may have a more severe reaction
on repeated challenge, either accidental, diagnostic or therapeutic. Such
patients may be unresponsive to the usual doses of epinephrine used to treat
the allergic reaction.
Major Surgery
Chronically administered beta-blocking therapy should not
be routinely withdrawn prior to major surgery, however the impaired ability of
the heart to respond to reflex adrenergic stimuli may augment the risks of
general anesthesia and surgical procedures.
Diabetes
In patients with diabetes (especially labile diabetes) or
with a history of episodes of spontaneous hypoglycemia, sotalol hydrochloride
tablets should be given with caution since beta-blockade may mask some
important premonitory signs of acute hypoglycemia; e.g., tachycardia.
Sick Sinus Syndrome
Sotalol hydrochloride tablets should be used only with
extreme caution in patients with sick sinus syndrome associated with
symptomatic arrhythmias, because it may cause sinus bradycardia, sinus pauses
or sinus arrest.
Thyrotoxicosis
Beta-blockade may mask certain clinical signs (e.g.,
tachycardia) of hyperthyroidism. Patients suspected of developing
thyrotoxicosis should be managed carefully to avoid abrupt withdrawal of
beta-blockade which might be followed by an exacerbation of symptoms of
hyperthyroidism, including thyroid storm.