Overview
DESCRIPTION Flecainide acetate is an antiarrhythmic drug available in tablets of 50 mg, 100 mg, or 150 mg for oral administration. Flecainide acetate is benzamide, N-(2-piperidinyl-methyl)-2,5-bis (2,2,2-trifluoroethoxy)-monoacetate. The structural formula is given below. Flecainide acetate USP is a white to slightly off-white, crystalline powder with a pK a of 9.3.
Mechanism of Action
CLINICAL PHARMACOLOGY Flecainide acetate has local anesthetic activity and belongs to the membrane stabilizing (Class 1) group of antiarrhythmic agents; it has electrophysiologic effects characteristic of the IC class of antiarrhythmics. Electrophysiology In man, flecainide acetate produces a dose-related decrease in intracardiac conduction in all parts of the heart with the greatest effect on the His-Purkinje system (H-V conduction). Effects upon atrioventricular (AV) nodal conduction time and intra-atrial conduction times, although present, are less pronounced than those on ventricular conduction velocity. Significant effects on refractory periods were observed only in the ventricle.
Indications
- 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...
Common Doses
- 50 mg
- 100 mg
- 300 mg
- 150 mg
Dosage
DOSAGE AND ADMINISTRATION For patients with sustained VT, no matter what their cardiac status, flecainide acetate tablets, 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.
Black Box Warning
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.
Contraindications
- CONTRAINDICATIONS Flecainide acetate tablets are contraindicated in patients with preexisting 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.
Side Effects
- 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...
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.