Flecainide
/api/v1/drug/flecainideBoxed warning
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.
Mechanism of action
Sourced from openFDAMechanism-of-action class: Ion Channel Interactions.
Indications
Sourced from openFDA- 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.ICD-10: I48.91
Contraindications
Sourced from openFDA- 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.contraindicated
Dosage & administration
Sourced from openFDAFor 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. 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 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 dose from 50 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.
Adverse reactions
Sourced from openFDAIn 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.
Use in specific populations
Sourced from openFDAPregnancy Pregnancy Category C . 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.
Overdosage
Sourced from openFDANo specific antidote has been identified for the treatment of flecainide acetate overdosage. Overdoses ranging up to 8000 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 1000 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.
Approval history
Sourced from openFDA- Jul 31, 2001ANDAANDA075442Amneal Pharm
- Oct 28, 2002ANDAANDA075882Ani Pharms
- Jan 14, 2003ANDAANDA076278Hikma
- Jul 9, 2009ANDAANDA079164Chartwell
- Nov 3, 2017ANDAANDA202821Aurobindo Pharma Ltd
- Sep 16, 2020ANDAANDA210683Regcon Holdings
- Sep 8, 2022ANDAANDA215599Yichang Humanwell
FAERS reports
- 1Atrial Fibrillation3446.7%
- 2Fatigue2835.5%
- 3Dyspnoea2755.4%
- 4Dizziness2625.1%
- 5Nausea2474.8%
- 6Drug Ineffective2204.3%
- 7Headache2154.2%
- 8Diarrhoea2144.2%
- 9Asthenia2024.0%
- 10Fall1843.6%
- 11Toxicity To Various Agents1733.4%
- 12Hypotension1713.4%
- 13Drug Interaction1693.3%
- 14Malaise1663.3%
- 15Cough1352.6%
Literature
Recent PubMed references pinned to Flecainide as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.
- [Severe flecainide poisoning successfully treated with lipid emulsion].Revue medicale de Liege · 2026 · Saive D, Berg J, Appoloni O, et al.PMID 41987541
- Reappraising Use of Flecainide for Atrial Fibrillation and Ventricular Arrhythmias in Structural Heart Disease Patients.Medicina (Kaunas, Lithuania) · 2025 · Tsiachris D, Kotoulas SC, Doundoulakis I, et al.PMID 41155832DOI 10.3390/medicina61101845
- Carvedilol versus flecainide treatment in idiopathic ventricular extrasystoles and tachycardias (CARFLECT IV) trial: Rationale and design.Revista portuguesa de cardiologia : orgao oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology · 2025 · Trincado Ave M, Brión M, Díaz Fernández B, et al.PMID 41110603DOI 10.1016/j.repc.2025.07.004
- Flecainide mediated sodium channel blockade enhances blood brain barrier integrity and promotes neuroprotection in neuroinflammation.Scientific reports · 2025 · Sindi M, Klees D, Dobelmann V, et al.PMID 40849530DOI 10.1038/s41598-025-15430-w
- Relevance of CYP2D6 in the Efficacy and Toxicity of Flecainide in Patients With Atrial Fibrillation: A Cohort Study.Journal of cardiovascular pharmacology · 2025 · Trincado Ave M, Brión M, Blanco-Verea A, et al.PMID 40705539DOI 10.1097/FJC.0000000000001739
- Long-term adherence to flecainide as a rhythm control therapy in recurrent atrial fibrillation - a retrospective cohort study.Scandinavian cardiovascular journal : SCJ · 2025 · Siotis A, Johansson S, Graff C, et al.PMID 40553490DOI 10.1080/14017431.2025.2525110
- The maternal exposure of digoxin and flecainide in relation to the safety and effectiveness in the treatment of non-hydropic fetal tachycardia.Heart rhythm · 2025 · Smeets RMA, van Beynum IM, van Kesteren C, et al.PMID 40412599DOI 10.1016/j.hrthm.2025.05.039
- Flecainide for the Treatment of Andersen-Tawil Syndrome.JACC. Clinical electrophysiology · 2025 · Mann TD, Yoruk A, Neves RA, et al.PMID 40372332DOI 10.1016/j.jacep.2025.03.020
Clinical trials
The 10 most recently updated of 74 ClinicalTrials.gov registrations naming Flecainide as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.
- Efficacy of Early Rhythm Control in AF With TR PatientsRecruiting · Observational · 5,800 enrolled · Samsung Medical CenterNCT07607093updated 2026-05-29
- Early Treatment of Atrial Fibrillation for Stroke Prevention Trial in Acute STROKERecruiting · Phase 3 · Interventional · 1,746 enrolled · Universitätsklinikum Hamburg-EppendorfNCT05293080updated 2026-05-18
- Pulsed Field Ablation (PFA) vs Anti-Arrhythmic Drug (AAD) Therapy as a First Line Treatment for Persistent Atrial FibrillationActive not recruiting · Interventional · 484 enrolled · Boston Scientific CorporationNCT06096337updated 2026-03-31
- Efficacy of Early Rhythm Control Therapy in Patients With Subclinical Atrial FibrillationRecruiting · Interventional · 520 enrolled · Samsung Medical CenterNCT07447297updated 2026-03-03
- Catheter Ablation Versus Anti-arrhythmic Drugs for Premature Ventricular ComplexesNot yet recruiting · Interventional · 40 enrolled · Western Sydney Local Health DistrictNCT07445334updated 2026-03-03
- Flecainide Safety in Patients With Coronary Artery Disease and Atrial FibrillationNot yet recruiting · Phase 4 · Interventional · 988 enrolled · Universitaire Ziekenhuizen KU LeuvenNCT07405671updated 2026-02-12
- EfFect of Ablation of Persistent AtriaL Fibrillation on COgNitive Function in Individuals With Mild Cognitive ImpairmentRecruiting · Interventional · 120 enrolled · Poitiers University HospitalNCT05790707updated 2026-01-23
- Dronedarone Rhythm Intervention for Early Atrial FibrillationNot yet recruiting · Phase 4 · Interventional · 1,898 enrolled · Inha University HospitalNCT07270848updated 2025-12-22
- Shortening Duration of Antiarrhythmic Medication for SVT in InfantsCompleted · Observational · 107 enrolled · Tampere University HospitalNCT04837261updated 2025-11-20
- The Use of Flecainide for Treatment of Atrial FibrillationCompleted · Observational · 50 enrolled · Lund UniversityNCT05084495updated 2025-09-11
Pharmacogenomics
CPIC-curated drug–gene pairs for Flecainide. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.
- CYP2D6CPIC B/C (provisional)ClinPGx 1A
Frequently asked questions
- How does Flecainide work?
- Mechanism-of-action class: Ion Channel Interactions.
- What is Flecainide used for?
- According to FDA labeling, Flecainide carries indications including: 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.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.
- What class of drug is Flecainide?
- Flecainide is classified as Antiarrhythmics, class Ic, Antiarrhythmic, Ion Channel Interactions, Cardiac Rhythm Alteration, Negative Inotropy.
- What are the contraindications for Flecainide?
- Flecainide labeling lists contraindications including: 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.. Always consult the full prescribing information and a clinician.
flecainide is illustrative MVP content compiled from public sources. pharmacopeia is for educational and informational use only and is not a substitute for professional medical advice.