Flecainide Acetate 50 mg Tablet, 30-count

WARNINGS Mortality Flecainide acetate was included in the National Heart Lung and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST), a long-term, multicenter, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had a myocardial infarction more than six days but less than two years previously. An excessive mortality or non-fatal cardiac arrest rate was seen in patients treated with flecainide acetate compared with that seen in patients assigned to a carefully matched placebo-treated group.

This rate was 16/315 (5.1%) for flecainide acetate and 7/309 (2.3%) for the matched placebo. The average duration of treatment with flecainide acetate in this study was ten months. The applicability of the CAST results to other populations (e.g., those without recent myocardial infarction) is uncertain, but at present, it is prudent to consider the risks of Class IC agents (including flecainide acetate), coupled with the lack of any evidence of improved survival, generally unacceptable in patients without life-threatening ventricular arrhythmias, even if the patients are experiencing unpleasant, but not life-threatening, symptoms or signs.

Ventricular Pro-Arrhythmic Effects in Patients with Atrial Fibrillation/Flutter A review of the world literature revealed reports of 568 patients treated with oral flecainide acetate for paroxysmal atrial fibrillation/flutter (PAF). Ventricular tachycardia was experienced in 0.4% (2/568) of these patients. Of 19 patients in the literature with chronic atrial fibrillation (CAF), 10.5% (2) experienced VT or VF.

FLECAINIDE IS NOT RECOMMENDED FOR USE IN PATIENTS WITH CHRONIC ATRIAL FIBRILLATION. Case reports of ventricular proarrhythmic effects in patients treated with flecainide acetate for atrial fibrillation/flutter have included increased PVCs, VT, ventricular fibrillation (VF), and death. As with other Class I agents, patients treated with flecainide acetate for atrial flutter have been reported with 1:1 atrioventricular conduction due to slowing the atrial rate.

A paradoxical increase in the ventricular rate also may occur in patients with atrial fibrillation who receive flecainide acetate. Concomitant negative chronotropic therapy such as digoxin or beta-blockers may lower the risk of this complication. PROARRHYTHMIC EFFECTS Flecainide acetate, like other antiarrhythmic agents, can cause new or worsened supraventricular or ventricular arrhythmias.

Ventricular proarrhythmic effects range from an increase in frequency of PVCs to the development of more severe ventricular tachycardia, e.g., tachycardia that is more sustained or more resistant to conversion to sinus rhythm, with potentially fatal consequences. In studies of ventricular arrhythmia patients treated with flecainide acetate, three-fourths of proarrhythmic events were new or worsened ventricular tachyarrhythmias, the remainder being increased frequency of PVCs or new supraventricular arrhythmias. In patients treated with flecainide for sustained ventricular tachycardia, 80% (51/64) of proarrhythmic events occurred within 14 days of the onset of therapy.

In studies of 225 patients with supraventricular arrhythmia (108 with paroxysmal supraventricular tachycardia and 117 with paroxysmal atrial fibrillation), there were 9 (4%) proarrhythmic events, 8 of them in patients with paroxysmal atrial fibrillation. Of the 9, 7 (including the one in a PSVT patient) were exacerbations of supraventricular arrhythmias (longer duration, more rapid rate, harder to reverse) while 2 were ventricular arrhythmias, including one fatal case of VT/VF and one wide complex VT (the patient showed inducible VT, however, after withdrawal of flecainide), both in patients with paroxysmal atrial fibrillation and known coronary artery disease.

It is uncertain if flecainide acetate's risk of proarrhythmia is exaggerated in patients with chronic atrial fibrillation (CAF), high ventricular rate, and/or exercise. W…

ADVERSE REACTIONS In post-myocardial infarction patients with asymptomatic PVCs and non-sustained ventricular tachycardia, flecainide acetate therapy was found to be associated with a 5.1% rate of death and non-fatal cardiac arrest, compared with a 2.3% rate in a matched placebo group. (See WARNINGS ). Adverse effects reported for flecainide acetate, described in detail in the WARNINGS section, were new or worsened arrhythmias which occurred in 1% of 108 patients with PSVT and in 7% of 117 patients with PAF; and new or exacerbated ventricular arrhythmias which occurred in 7% of 1330 patients with PVCs, non-sustained or sustained VT.

In patients treated with flecainide for sustained VT, 80% (51/64) of proarrhythmic events occurred within 14 days of the onset of therapy. 198 patients with sustained VT experienced a 13% incidence of new or exacerbated ventricular arrhythmias when dosage was initiated at 200 mg/day with slow upward titration, and did not exceed 300 mg/day in most patients. In some patients, flecainide acetate treatment has been associated with episodes of unresuscitatable VT or ventricular fibrillation (cardiac arrest).

(See WARNINGS ). New or worsened CHF occurred in 6.3% of 1046 patients with PVCs, non-sustained or sustained VT. Of 297 patients with sustained VT, 9.1% experienced new or worsened CHF.

New or worsened CHF was reported in 0.4% of 225 patients with supraventricular arrhythmias. There have also been instances of second- (0.5%) or third-degree (0.4%) AV block. Patients have developed sinus bradycardia, sinus pause, or sinus arrest, about 1.2% altogether (See WARNINGS ).

The frequency of most of these serious adverse events probably increases with higher trough plasma levels, especially when these trough levels exceed 1 mcg/mL. There have been rare reports of isolated elevations of serum alkaline phosphatase and isolated elevations of serum transaminase levels. These elevations have been asymptomatic and no cause and effect relationship with flecainide acetate has been established.

In foreign postmarketing surveillance studies, there have been rare reports of hepatic dysfunction including reports of cholestasis and hepatic failure, and extremely rare reports of blood dyscrasias. Although no cause and effect relationship has been established, it is advisable to discontinue flecainide acetate in patients who develop unexplained jaundice or signs of hepatic dysfunction or blood dyscrasias in order to eliminate flecainide acetate as the possible causative agent. Incidence figures for other adverse effects in patients with ventricular arrhythmias are based on a multicenter efficacy study, utilizing starting doses of 200 mg/day with gradual upward titration to 400 mg/day.

Patients were treated for an average of 4.7 months, with some receiving up to 22 months of therapy. In this trial, 5.4% of patients discontinued due to non-cardiac adverse effects. Table 1: Most Common Non-Cardiac Adverse Effects in Ventricular Arrhythmia Patients Treated with Flecainide Acetate in the Multicenter Study * Dizziness includes reports of dizziness, lightheadedness, faintness, unsteadiness, near syncope, etc. † Visual disturbance includes reports of blurred vision, difficulty in focusing, spots before eyes, etc.

Adverse Effect Incidence Incidence by Dose During Upward Titration All 429 Patients at Any Dose 200 mg/Day (N=426) 300 mg/Day (N=293) 400 mg/Day (N=100) Dizziness* 18.9% 11% 10.6% 13% Visual Disturbances† 15.9% 5.4% 12.3% 18% Dyspnea 10.3% 5.2% 7.5% 4% Headache 9.6% 4.5% 6.1% 9% Nausea 8.9% 4.9% 4.8% 6% Fatigue 7.7% 4.5% 4.4% 3% Palpitation 6.1% 3.5% 2.4% 7% Chest Pain 5.4% 3.1% 3.8% 1% Asthenia 4.9% 2.6% 2% 4% Tremor 4.7% 2.4% 3.4% 2% Constipation 4.4% 2.8% 2.1% 1% Edema 3.5% 1.9% 1.4% 2% Abdominal Pain 3.3% 1.9% 2.4% 1% The following additional adverse experiences, possibly related to flecainide acetate therapy and occurring in 1% to less than 3% of patients, have been reported in acute and chronic studies: Body as a…

Drug Interactions Flecainide acetate has been administered to patients receiving digitalis preparations or beta-adrenergic blocking agents without adverse effects. During administration of multiple oral doses of flecainide acetate to healthy subjects stabilized on a maintenance dose of digoxin , a 13% to 19% increase in plasma digoxin levels occurred at six hours postdose. In a study involving healthy subjects receiving flecainide acetate and propranolol concurrently, plasma flecainide levels were increased about 20% and propranolol levels were increased about 30% compared to control values.

In this formal interaction study, flecainide acetate and propranolol were each found to have negative inotropic effects; when the drugs were administered together, the effects were additive. The effects of concomitant administration of flecainide acetate and propranolol on the PR interval were less than additive. In flecainide acetate clinical trials, patients who were receiving beta blockers concurrently did not experience an increased incidence of side effects.

Nevertheless, the possibility of additive negative inotropic effects of beta blockers and flecainide should be recognized. Flecainide is not extensively bound to plasma proteins. In vitro studies with several drugs which may be administered concomitantly showed that the extent of flecainide binding to human plasma proteins is either unchanged or only slightly less.

Consequently, interactions with other drugs which are highly protein bound (e.g., anticoagulants ) would not be expected. Flecainide acetate has been used in a large number of patients receiving diuretics without apparent interaction. Limited data in patients receiving known enzyme inducers ( phenytoin , phenobarbital , carbamazepine ) indicate only a 30% increase in the rate of flecainide elimination.

In healthy subjects receiving cimetidine (1 gm daily) for one week, plasma flecainide levels increased by about 30% and half-life increased by about 10%. When amiodarone is added to flecainide therapy, plasma flecainide levels may increase two-fold or more in some patients, if flecainide dosage is not reduced. (See DOSAGE AND ADMINISTRATION ).

Drugs that inhibit cytochrome P450IID6, such as quinidine , might increase the plasma concentrations of flecainide in patients that are on chronic flecainide therapy; especially if these patients are extensive metabolizers. There has been little experience with the coadministration of flecainide acetate and either disopyramide or verapamil . Because both of these drugs have negative inotropic properties and the effects of coadministration with flecainide acetate are unknown, neither disopyramide nor verapamil should be administered concurrently with flecainide unless, in the judgment of the physician, the benefits of this combination outweigh the risks.

There has been too little experience with the coadministration of flecainide acetate with nifedipine or diltiazem to recommend concomitant use.