Propafenone - Warnings and Precautions
The following warnings and precautions are taken directly from the US FDA-approved drug label for Propafenone. This is the same information dispensing pharmacists read.
\u26a0\ufe0f Boxed Warning (Highest FDA Alert)
WARNING: MORTALITY In the National Heart, Lung, and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a long-term, multicenter, randomized, double-blind trial in patients with asymptomatic non-life-threatening ventricular arrhythmias who had a myocardial infarction more than 6 days but less than 2 years previously, an increased rate of death or reversed cardiac arrest rate (7.7%; 56/730) was seen in patients treated with encainide or flecainide (Class IC antiarrhythmics) compared with that seen in patients assigned to placebo (3%; 22/725). The average duration of treatment with encainide or flecainide in this trial was 10 months. The applicability of the CAST results to other populations (e.g., those without recent myocardial infarction) or other antiarrhythmic drugs is uncertain, but at present, it is prudent to consider any IC antiarrhythmic to have a significant proarrhythmic risk in patients with structural heart disease. Given the lack of any evidence that these drugs improve survival, antiarrhythmic agents should generally be avoided in patients with non-life-threatening ventricular arrhythmias, even if the patients are experiencing unpleasant, but not life-threatening, symptoms or signs. WARNING: MORTALITY See full prescribing information for complete boxed warning. An increased rate of death or reversed cardiac arrest rate was seen in patients treated with encainide or flecainide (Class IC antiarrhythmics) compared with that seen in patients assigned to p
5 WARNINGS AND PRECAUTIONS May cause new or worsened arrhythmias.
Evaluate patients via ECG prior to and during therapy.
Propafenone hydrochloride extended-release capsules may unmask Brugada or Brugada-like Syndrome.
Evaluate patients via ECG after initiation of therapy. ( 4 , 5.2 ) Avoid use with other antiarrhythmic agents or drugs that prolong the QT interval.
Avoid simultaneous use of propafenone with both a cytochrome P450 2D6 (CYP2D6) inhibitor and a 3A4 inhibitor (CYP3A4).
May provoke overt heart failure.
May cause dose-related first-degree AV block or other conduction disturbances.
Should not be given to patients with conduction defects in absence of a pacemaker.
May affect artificial pacemakers.
Pacemakers should be monitored during therapy.
Agranulocytosis: Patients should report signs of infection.
Administer cautiously to patients with impaired hepatic and renal function. ( 5.9 , 5.10 ) Exacerbation of myasthenia gravis has been reported.
5.1 Proarrhythmic Effects Propafenone has caused new or worsened arrhythmias.
Such proarrhythmic effects include sudden death and life-threatening ventricular arrhythmias such as ventricular fibrillation, ventricular tachycardia, asystole, and torsade de pointes.
It may also worsen premature ventricular contractions or supraventricular arrhythmias, and it may prolong the QT interval.
It is therefore essential that each patient given propafenone hydrochloride extended-release capsules be evaluated electrocardiographically prior to and during therapy to determine whether the response to propafenone hydrochloride extended-release capsules supports continued treatment.
Because propafenone prolongs the QRS interval in the electrocardiogram, changes in the QT interval are difficult to interpret [see Clinical Pharmacology ] .
In the propafenone hydrochloride extended-release capsules Atrial Fibrillation Trial (RAFT) trial [see Clinical Studies ] , there were too few deaths to assess the long-term risk to patients.
There were 5 deaths, 3 in the pooled group for propafenone hydrochloride extended-release capsules (0.8%), and 2 in the placebo group (1.6%).
In the overall database of 8 trials of propafenone hydrochloride extended-release capsules and propafenone hydrochloride immediate-release, the mortality rate was 2.5% per year on propafenone and 4% per year on placebo.
Concurrent use of propafenone with other antiarrhythmic agents has not been well studied.
In a U.S. uncontrolled, open-label, multicenter trial using the immediate-release formulation in patients with symptomatic supraventricular tachycardia (SVT), 1.9% (9/474) of these patients experienced ventricular tachycardia (VT) or ventricular fibrillation (VF) during the trial.
However, in 4 of the 9 patients, the ventricular tachycardia was of atrial origin.
Six of the 9 patients that developed ventricular arrhythmias did so within 14 days of onset of therapy.
About 2.3% (11/474) of all patients had recurrence of SVT during the trial which could have been a change in the patients' arrhythmia behavior or could represent a proarrhythmic event.
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