FLECAINIDE ACETATE

Clinical safety rating: safe

Animal studies have demonstrated safety

How it works

Class Ic antiarrhythmic agent; sodium channel blocker with slow kinetics of dissociation, slowing conduction velocity with minimal effect on repolarization.

What the body does with it

Metabolism	Primarily hepatic via CYP2D6; active metabolite meta-O-dealkylated flecainide; renal excretion of unchanged drug and metabolites.
Excretion	Renal: approximately 85% (10-50% unchanged, the rest as meta-O-dealkylated metabolites); fecal/biliary: minor (<5%).
Half-life	Terminal half-life 12-27 hours (mean 20 hours) in patients with normal renal function; may increase to 20-40 hours in renal impairment (CrCl <35 mL/min).
Protein binding	Approximately 40-50% bound to plasma proteins (mainly albumin and alpha-1-acid glycoprotein).
Volume of Distribution	Apparent Vd 5-13 L/kg (mean 9 L/kg), indicating extensive tissue distribution.
Bioavailability	Oral: 90-95% (high, with minimal first-pass metabolism).
Onset of Action	Oral: 1-2 hours; intravenous: within minutes.
Duration of Action	Oral: 12-24 hours (dosing every 12 hours); intravenous: 4-6 hours.

Classification & Brands

Dosing & administration

Initial: 100 mg every 12 hours; increase by 50 mg twice daily every 4 days; maximum 400 mg/day. Oral route.

Dosage form	TABLET
Renal impairment	CrCl >50 mL/min: no adjustment; CrCl 35-50 mL/min: decrease dose by 25%; CrCl <35 mL/min: not recommended or use with extreme caution, dose at 50% reduction with careful monitoring.
Liver impairment	Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 25-50%; Child-Pugh Class C: avoid use or reduce dose by 50% with close monitoring.
Pediatric use	For supraventricular tachycardia: 1-3 mg/kg/day orally divided every 8-12 hours; maximum 8 mg/kg/day; for ventricular arrhythmias: 2-6 mg/kg/day orally divided every 8-12 hours; maximum 8 mg/kg/day.
Geriatric use	Start at 50-100 mg every 12 hours; increase cautiously due to reduced renal function and increased risk of proarrhythmia; monitor renal function and ECG.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Other drugs that prolong the QT interval increase risk of proarrhythmia Can cause new or worsened arrhythmias.

Breastfeeding	Flecainide is excreted in human milk; milk-to-plasma (M/P) ratio approximately 2.5. Infant exposure estimated at 0.4% of maternal weight-adjusted dose. No reports of adverse effects in breastfed infants; however, caution due to potential for bradycardia and proarrhythmia.
Teratogenic Risk	Flecainide crosses the placenta. First trimester: Limited human data; animal studies show no major teratogenicity but embryo-fetal toxicity at high doses. Second and third trimesters: Use only if maternal benefit outweighs fetal arrhythmia risk; may cause fetal bradycardia. Fetal/neonatal adverse effects include proarrhythmia, negative inotropy.

Warnings & precautions

■ FDA Black Box Warning

None (however, Class Ic drugs are contraindicated in patients with structural heart disease due to increased mortality in CAST trial).

Side Effect Profile

Common Effects	atrial fibrillation
Serious Effects

Absolute Contraindications

["Hypersensitivity to flecainide or any component","Cardiogenic shock","Pre-existing second- or third-degree AV block (unless pacemaker present)","Bifascicular block (unless pacemaker present)","Structural heart disease (e.g., post-MI, ischemic heart disease, left ventricular dysfunction, cardiomyopathy)"]

Clinical Precautions

Precautions

["Proarrhythmic effects (worsening arrhythmias or new arrhythmias)","Use with structural heart disease (especially post-MI) increases risk of cardiac arrest","Heart failure or left ventricular dysfunction","Electrolyte disturbances (hypokalemia, hypomagnesemia)","Renal impairment (dose reduction needed)","Hepatic impairment","Conduction disturbances (pre-existing sinus node dysfunction, second- or third-degree AV block)","Pacemaker-dependent patients (increase pacing threshold)","Ocular effects (corneal deposits, visual disturbances)"]

Drug interactions

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FLECAINIDE ACETATE

Clinical safety rating: safe

Animal studies have demonstrated safety

How it works

Class Ic antiarrhythmic agent; sodium channel blocker with slow kinetics of dissociation, slowing conduction velocity with minimal effect on repolarization.

What the body does with it

Metabolism	Primarily hepatic via CYP2D6; active metabolite meta-O-dealkylated flecainide; renal excretion of unchanged drug and metabolites.
Excretion	Renal: approximately 85% (10-50% unchanged, the rest as meta-O-dealkylated metabolites); fecal/biliary: minor (<5%).
Half-life	Terminal half-life 12-27 hours (mean 20 hours) in patients with normal renal function; may increase to 20-40 hours in renal impairment (CrCl <35 mL/min).
Protein binding	Approximately 40-50% bound to plasma proteins (mainly albumin and alpha-1-acid glycoprotein).
Volume of Distribution	Apparent Vd 5-13 L/kg (mean 9 L/kg), indicating extensive tissue distribution.
Bioavailability	Oral: 90-95% (high, with minimal first-pass metabolism).
Onset of Action	Oral: 1-2 hours; intravenous: within minutes.
Duration of Action	Oral: 12-24 hours (dosing every 12 hours); intravenous: 4-6 hours.

Classification & Brands

Dosing & administration

Initial: 100 mg every 12 hours; increase by 50 mg twice daily every 4 days; maximum 400 mg/day. Oral route.

Dosage form	TABLET
Renal impairment	CrCl >50 mL/min: no adjustment; CrCl 35-50 mL/min: decrease dose by 25%; CrCl <35 mL/min: not recommended or use with extreme caution, dose at 50% reduction with careful monitoring.
Liver impairment	Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 25-50%; Child-Pugh Class C: avoid use or reduce dose by 50% with close monitoring.
Pediatric use	For supraventricular tachycardia: 1-3 mg/kg/day orally divided every 8-12 hours; maximum 8 mg/kg/day; for ventricular arrhythmias: 2-6 mg/kg/day orally divided every 8-12 hours; maximum 8 mg/kg/day.
Geriatric use	Start at 50-100 mg every 12 hours; increase cautiously due to reduced renal function and increased risk of proarrhythmia; monitor renal function and ECG.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Other drugs that prolong the QT interval increase risk of proarrhythmia Can cause new or worsened arrhythmias.

Breastfeeding	Flecainide is excreted in human milk; milk-to-plasma (M/P) ratio approximately 2.5. Infant exposure estimated at 0.4% of maternal weight-adjusted dose. No reports of adverse effects in breastfed infants; however, caution due to potential for bradycardia and proarrhythmia.
Teratogenic Risk	Flecainide crosses the placenta. First trimester: Limited human data; animal studies show no major teratogenicity but embryo-fetal toxicity at high doses. Second and third trimesters: Use only if maternal benefit outweighs fetal arrhythmia risk; may cause fetal bradycardia. Fetal/neonatal adverse effects include proarrhythmia, negative inotropy.

Warnings & precautions

■ FDA Black Box Warning

None (however, Class Ic drugs are contraindicated in patients with structural heart disease due to increased mortality in CAST trial).

Side Effect Profile

Common Effects	atrial fibrillation
Serious Effects

FLECAINIDE ACETATE

How it works

What the body does with it

Classification & Brands

Dosing & administration

Use during pregnancy

Warnings & precautions

Side Effect Profile

Absolute Contraindications

Clinical Precautions

Drug interactions

FLECAINIDE ACETATE

How it works

What the body does with it

Classification & Brands

Dosing & administration

Use during pregnancy

Warnings & precautions

Side Effect Profile

Absolute Contraindications

Clinical Precautions

Drug interactions

Clinical Tips & Counseling