Flec-EM

What it is

Flec-EM contains flecainide acetate in 50 mg and 100 mg tablet strengths. The 50 mg tablets are white to off-white circular biconvex tablets debossed with F1, with an approximate diameter of 6.5 mm, while the 100 mg tablets are white to off-white circular biconvex tablets debossed with F & 2 separated by a scoreline, with an approximate diameter of 8.8 mm. Flecainide acetate belongs to the membrane stabilising (Class 1) group of antiarrhythmic agents.

Approved indications

— Supraventricular arrhythmias due to pre-excitation syndromes such as Wolff-Parkinson-White and Lown-Ganong-Levine syndromes. — Supraventricular arrhythmias due to dual AV nodal pathways in patients with debilitating symptoms. — Paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms. — Life-threatening ventricular arrhythmias not controlled by other drugs, used for continuous maintenance of normal rhythm following initial oral or intravenous therapy or conversion by other means.

Dosing overview

The dosage of Flecainide acetate must be adjusted to the individual needs of each patient based on therapeutic response and tolerance, and dosage may need to be modified based on the age, weight or clinical status of the patient. 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. In patients with severe renal impairment (creatinine clearance of 20 mL/min/m² or less), the initial dosage should be 100 mg once daily (or 50 mg twice daily).

Key safety warnings

In the Cardiac Arrhythmia Suppression Trial (CAST), oral flecainide was associated with a higher incidence of mortality or non-fatal cardiac arrest (19/323) compared with placebo (7/318) in patients with asymptomatic non-life-threatening ventricular arrhythmias who had myocardial infarction more than six days but less than two years previously, with an even higher incidence of mortality observed in flecainide-treated patients with more than one myocardial infarction. Patients with structural heart disease treated with flecainide for supraventricular arrhythmias may be at increased risk for proarrhythmia and cardiac adverse events, with use associated with life-threatening and occasionally fatal ventricular arrhythmias; therefore, in these patients, especially in the presence of impaired left ventricular function with ejection fraction ≤ 40%, flecainide should be used with extreme caution, preferably after other antiarrhythmic drugs have been tried or considered inappropriate. Flecainide acetate is not recommended for use in patients with chronic atrial fibrillation. Because flecainide acetate has a mild negative inotropic effect, it may cause or worsen congestive heart failure, particularly in patients with cardiomyopathy, pre-existing severe heart failure (NYHA functional class III or IV) or ejection fractions ≤ 40%; therefore, flecainide acetate should be used cautiously in patients who are known to have a history of congestive heart failure or myocardial dysfunction. Flecainide acetate slows cardiac conduction sufficiently in most patients to produce measurable increases in the duration of the PR, QRS and QT intervals on the electrocardiogram, with increases of more than 25% in the duration of the PR interval occurring commonly and approximately one-third of patients developing first-degree heart block, while widening of the QRS of 25% or more is also common.

Contraindications

— Second or third degree A-V block, unless a pacemaker is present to sustain rhythm. — Right bundle branch block when associated with a left hemi-block (bifascicular block) unless a pacemaker is present to sustain rhythm. — Cardiogenic shock. — Asymptomatic premature ventricular contractions and/or asymptomatic non-sustained ventricular tachycardia in patients with a history of myocardial infarction. — Known hypersensitivity to the drug. — Severe renal or hepatic impairment unless plasma level monitoring can be done.

Regulatory history

Flec-EM flecainide acetate 50 mg and 100 mg tablet blister packs were first listed on the ARTG on 27 May 2020 under licence category RE (registered entered).