Flecainide Acetate

Description

DESCRIPTION Flecainide Acetate Tablets, USP are an antiarrhythmic drug containing 50 mg, 100 mg or 150 mg of flecainide acetate USP for oral administration. Flecainide acetate USP is benzamide, N-(2-piperidinylmethyl)-2,5-bis(2,2,2-trifluoroethoxy)-monoacetate. The structural formula is given below. Flecainide acetate USP is a white crystalline substance with a pKa of 9.3. It has an aqueous solubility of 48.4 mg/mL at 37°C. Flecainide Acetate Tablets, USP also contain: croscarmellose sodium, magnesium stearate, microcrystalline cellulose, and pregelatinized starch. Flecainide Acetate Tablets, USP meets USP Dissolution Test 2.

What Is Flecainide Acetate Used For?

INDICATIONS AND USAGE In patients without structural heart disease, Flecainide Acetate Tablets, USP are indicated for the prevention of: paroxysmal supraventricular tachycardias (PSVT), including atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia and other supraventricular tachycardias of unspecified mechanism associated with disabling symptoms paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms Flecainide Acetate Tablets, USP are also indicated for the prevention of: documented ventricular arrhythmias, such as sustained ventricular tachycardia ( sustained VT), that in the judgment of the physician are life-threatening. Use of Flecainide Acetate Tablets, USP for the treatment of sustained VT, like other antiarrhythmics, should be initiated in the hospital. The use of Flecainide Acetate Tablets, USP is not recommended in patients with less severe ventricular arrhythmias even if the patients are symptomatic. Because of the proarrhythmic effects of Flecainide Acetate Tablets, USP, its use should be reserved for patients in whom, in the opinion of the physician, the benefits of treatment outweigh the risks. Flecainide Acetate Tablets, USP should not be used in patients with recent myocardial infarction. (See Boxed WARNINGS .) Use of Flecainide Acetate Tablets, USP in chronic atrial fibrillation has not been adequately studied and is not recommended. (See Boxed WARNINGS .) As is the case for other antiarrhythmic agents, there is no evidence from controlled trials that the use of Flecainide Acetate Tablets, USP favorably affects survival or the incidence of sudden death.

Dosage and Administration

DOSAGE AND ADMINISTRATION For patients with sustained VT, no matter what their cardiac status, Flecainide Acetate Tablets, USP like other antiarrhythmics, should be initiated in-hospital with rhythm monitoring. Flecainide has a long half-life (12 to 27 hours in patients). Steady-state plasma levels, in patients with normal renal and hepatic function, may not be achieved until the patient has received 3 to 5 days of therapy at a given dose. Therefore, increases in dosage should be made no more frequently than once every four days , since during the first 2 to 3 days of therapy the optimal effect of a given dose may not be achieved. For patients with PSVT and patients with PAF the recommended starting dose is 50 mg every 12 hours. Flecainide Acetate Tablets, USP doses may be increased in increments of 50 mg bid every four days until efficacy is achieved. For PAF patients, a substantial increase in efficacy without a substantial increase in discontinuations for adverse experiences may be achieved by increasing the Flecainide Acetate Tablets, USP dose from 50 mg to 100 mg bid. The maximum recommended dose for patients with paroxysmal supraventricular arrhythmias is 300 mg/day. For sustained VT the recommended starting dose is 100 mg every 12 hours. This dose may be increased in increments of 50 mg bid every four days until efficacy is achieved. Most patients with sustained VT do not require more than 150 mg every 12 hours (300 mg/day), and the maximum dose recommended is 400 mg/day. In patients with sustained VT, use of higher initial doses and more rapid dosage adjustments have resulted in an increased incidence of proarrhythmic events and CHF, particularly during the first few days of dosing (see WARNINGS ) . Therefore, a loading dose is not recommended. Intravenous lidocaine has been used occasionally with Flecainide Acetate Tablets, USP while awaiting the therapeutic effect of Flecainide Acetate Tablets, USP. No adverse drug interactions were apparent. However, no formal studies have been performed to demonstrate the usefulness of this regimen. An occasional patient not adequately controlled by (or intolerant to) a dose given at 12-hour intervals may be dosed at eight-hour intervals. Once adequate control of the arrhythmia has been achieved, it may be possible in some patients to reduce the dose as necessary to minimize side effects or effects on conduction. In such patients, efficacy at the lower dose should be evaluated. Flecainide Acetate Tablets, USP should be used cautiously in patients with a history of CHF or myocardial dysfunction (see WARNINGS ) . Any use of Flecainide Acetate Tablets, USP in children should be directly supervised by a cardiologist skilled in the treatment of arrhythmias in children. Because of the evolving nature of information in this area, specialized literature should be consulted. Under six months of age, the initial starting dose of Flecainide Acetate Tablets, USP in children is approximately 50 mg/M 2 body...

Side Effects (Adverse Reactions)

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 1,330 patients with PVCs, non-sustained or sustained VT. In patients treated with flecainide acetate 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 1,046 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 Effects in Ventricular Arrhythmia Patients Treated with Flecainide Acetate in the Multicenter Study Adverse Effect Incidence All 429 Patients at Any Dose Incidence by Dose During Upward Titration 200 mg/Day (N=426) 300 mg/Day (N=293) 400 mg/Day (N=100) Dizziness Dizziness includes reports of dizziness, lightheadedness, faintness, unsteadiness, near syncope, etc. 18.9% 11.0% 10.6% 13.0% Visual Disturbances Visual disturbance includes reports of blurred vision, difficulty in focusing, spots before eyes, etc. 15.9% 5.4% 12.3% 18.0% Dyspnea 10.3% 5.2% 7.5% 4.0% Headache 9.6% 4.5% 6.1% 9.0% Nausea 8.9% 4.9% 4.8% 6.0% Fatigue 7.7% 4.5% 4.4% 3.0% Palpitation 6.1% 3.5% 2.4% 7.0% Chest Pain 5.4% 3.1% 3.8% 1.0% Asthenia 4.9% 2.6% 2.0% 4.0% Tremor 4.7% 2.4% 3.4% 2.0% Constipation 4.4% 2.8% 2.1% 1.0% Edema 3.5% 1.9% 1.4% 2.0% Abdominal Pain 3.3% 1.9% 2.4% 1.0% 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...

Drug Interactions

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 acetate therapy, plasma flecainide levels may increase two-fold or more in some patients, if flecainide acetate 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 acetate 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...

Contraindications

CONTRAINDICATIONS Flecainide Acetate Tablets are contraindicated in patients with pre-existing second- or third-degree AV block, or with right bundle branch block when associated with a left hemiblock (bifascicular block), unless a pacemaker is present to sustain the cardiac rhythm should complete heart block occur. Flecainide Acetate Tablets are also contraindicated in the presence of cardiogenic shock or known hypersensitivity to the drug.

Pregnancy and Breastfeeding

Pregnancy Flecainide has been shown to have teratogenic effects (club paws, sternebrae and vertebrae abnormalities, pale hearts with contracted ventricular septum) and an embryotoxic effect (increased resorptions) in one breed of rabbit (New Zealand White) when given doses of 30 and 35 mg/kg/day, but not in another breed of rabbit (Dutch Belted) when given doses up to 30 mg/kg/day. No teratogenic effects were observed in rats and mice given doses up to 50 and 80 mg/kg/day, respectively; however, delayed sternebral and vertebral ossification was observed at the high dose in rats. Because there are no adequate and well-controlled studies in pregnant women, flecainide acetate should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers Results from a multiple dose study conducted in mothers soon after delivery indicates that flecainide is excreted in human breast milk in concentrations as high as 4 times (with average levels about 2.5 times) corresponding plasma levels; assuming a maternal plasma level at the top of the therapeutic range (1 mcg/mL), the calculated daily dose to a nursing infant (assuming about 700 mL breast milk over 24 hours) would be less than 3 mg.

Overdosage

OVERDOSAGE No specific antidote has been identified for the treatment of flecainide acetate overdosage. Overdoses ranging up to 8,000 mg have been survived, with peak plasma flecainide concentrations as high as 5.3 mcg/mL. Untoward effects in these cases included nausea and vomiting, convulsions, hypotension, bradycardia, syncope, extreme widening of the QRS complex, widening of the QT interval, widening of the PR interval, ventricular tachycardia, AV nodal block, asystole, bundle branch block, cardiac failure, and cardiac arrest. The spectrum of events observed in fatal cases was much the same as that seen in the non-fatal cases. Death has resulted following ingestion of as little as 1,000 mg; concomitant overdose of other drugs and/or alcohol in many instances undoubtedly contributed to the fatal outcome. Treatment of overdosage should be supportive and may include the following: removal of unabsorbed drug from the gastrointestinal tract, administration of inotropic agents or cardiac stimulants such as dopamine, dobutamine or isoproterenol; mechanically assisted respiration; circulatory assists such as intra-aortic balloon pumping; and transvenous pacing in the event of conduction block. Because of the long plasma half-life of flecainide (12 to 27 hours in patients receiving usual doses), and the possibility of markedly non-linear elimination kinetics at very high doses, these supportive treatments may need to be continued for extended periods of time. Hemodialysis is not an effective means of removing flecainide from the body. Since flecainide elimination is much slower when urine is very alkaline (pH 8 or higher), theoretically, acidification of urine to promote drug excretion may be beneficial in overdose cases with very alkaline urine. There is no evidence that acidification from normal urinary pH increases excretion.

How Supplied

HOW SUPPLIED Flecainide Acetate Tablets, USP 100 mg tablet is supplied as a white biconvex round tablet with “YH 717” debossed on one side and have a score on the other side. NDC 71335-3063-1: 30 TABLETs in a BOTTLE NDC 71335-3063-2: 60 TABLETs in a BOTTLE NDC 71335-3063-3: 90 TABLETs in a BOTTLE NDC 71335-3063-4: 180 TABLETs in a BOTTLE NDC 71335-3063-5: 100 TABLETs in a BOTTLE Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature.] Dispense in a tight, light-resistant container as defined in the USP with a child-resistant closure. KEEP THIS AND ALL DRUGS OUT OF THE REACH OF CHILDREN. Repackaged/Relabeled by: Bryant Ranch Prepack Burbank, CA 91504