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Flecainide Side Effects

Medically reviewed by Drugs.com. Last updated on Nov 26, 2023.

Applies to flecainide: oral tablet.

Warning

Oral route (Tablet)

Excessive mortality or nonfatal cardiac arrest rate was seen in patients with asymptomatic non-life-threatening ventricular arrhythmias and with myocardial infarction for more than six days but less than two years previously who received flecainide, compared with patients assigned to a carefully matched placebo in the Cardiac Arrhythmia Suppression Trial (CAST). Consider the risks of Class IC agents (including flecainide) and the lack of evidence of improved survival, which is generally unacceptable in a patient without life-threatening ventricular arrhythmias, even if the patient is experiencing unpleasant, but not life-threatening, symptoms or signs. Flecainide is not recommended for use in patients with chronic atrial fibrillation. Case reports of ventricular proarrhythmic effects in patients treated with flecainide for atrial fibrillation/flutter have included increased premature ventricular contractions, ventricular tachycardia, ventricular fibrillation, and death.

Serious side effects of Flecainide

Along with its needed effects, flecainide may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking flecainide:

More common

Less common

Rare

Other side effects of Flecainide

Some side effects of flecainide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

Rare

For Healthcare Professionals

Applies to flecainide: oral tablet.

General

The Cardiac Arrhythmia Suppression Trial (CAST) revealed significantly higher mortality associated with flecainide in patients with a recent history (more than six days but less than two years prior to study) of myocardial infarction (MI) and non-life-threatening ventricular ectopy relative to placebo (5.1% versus 2.3%). The risk of death relative to placebo in patients with a recent history of Q-wave MI and non-Q-wave MI is 8.7 and 1.7, respectively. Use of flecainide in this context is potentially harmful.

Side effects are more likely when plasma flecainide concentrations are greater than 1.0 mcg/mL.[Ref]

Cardiovascular

Cardiovascular side effects including arrhythmias are the most serious side effects. Flecainide may cause or exacerbate arrhythmias in 1% of patients with preexisting paroxysmal supraventricular tachycardia and in 7% of patients with paroxysmal atrial fibrillation. Flecainide may also exacerbate arrhythmias in 7% to 13% of patients with preexisting sustained or nonsustained ventricular arrhythmias.

Flecainide-induced arrhythmias include sinus bradycardia or arrest in 2%, bundle branch blocks in 1%, increased premature ventricular depolarizations in 1%, ventricular tachycardia or fibrillation in 0.5%, and sudden death in 0.2% of patients. New ventricular arrhythmias have been reported in 3.4% of patients.

Flecainide may cause prolongation of the PR, QRS, and corrected QT intervals. Most of the QT interval prolongation is attributable to widening of the QRS complex rather than prolongation of the JT interval. Rare cases of torsades de pointes have been reported.

Exacerbation of congestive heart failure is rare and only occurs in about 0.5% and 9% of patients with preexisting supraventricular arrhythmias and ventricular arrhythmias, respectively. Hypotension is almost exclusively associated with intravenous administration of flecainide.[Ref]

Risk factors for a proarrhythmic effect include underlying congenital or structural heart disease.

A case of "pseudoinfarction" has been reported in which flecainide induced a transient right bundle branch block with a focal block in the septal fibers of the left bundle branch system. An electrocardiogram (ECG) also revealed ST segment elevations and a Q-wave pattern, consistent with septal infarction. The patient did not have a myocardial infarction by enzyme studies, and the ECG abnormalities resolved after discontinuation of flecainide.

One patient with a history of ischemic congestive heart failure, myocardial infarction (MI), and ventricular arrhythmias developed profound cardiogenic shock without evidence of MI or a new or worsened ventricular arrhythmia. The associated serum flecainide concentration was 1.8 mcg/mL.[Ref]

Nervous system

Nervous system side effects, such as dizziness and visual disturbances (including blurred vision, decreased acuity, and scotomata) occur in 13% to 28% of patients who are taking flecainide doses of 400 mg per day. Transient headaches, asthenia, feelings of a thick tongue or lips, fatigue, paresthesias, and tremors have been reported in 2% to 10% of patients.[Ref]

Flecainide may exacerbate myasthenia gravis.

At least 6 cases of flecainide-induced peripheral neuropathy (sensory loss) have been reported and it appears to develop after prolonged use ( 2 to 10 years). Following discontinuation of flecainide therapy, symptoms (e.g., lower-extremity weakness and/or paresthesias, gait disturbance) resolved over 3 to 6 months. However, in some cases the neuropathy did not resolve after discontinuation of flecainide.[Ref]

Gastrointestinal

Gastrointestinal side effects include abdominal pain, nausea, and constipation in 1% to 4% of patients. Diarrhea occurs rarely.[Ref]

Musculoskeletal

Musculoskeletal side effects including weakness has been reported and may be more likely in patients with underlying muscular disorders.[Ref]

A 33-year-old woman with atrial fibrillation, mitral valve prolapse, and a congenital muscle fiber disproportion myopathy developed muscle weakness which partially resolved after flecainide dosage reduction and completely resolved after substitution of flecainide with other antiarrhythmic agents.[Ref]

Ocular

Ocular side effects are limited to rare cases of corneal deposits.[Ref]

High performance liquid chromatographic analysis of excised corneal deposits in one patient revealed opacities with the same chromatographic characteristics of flecainide.[Ref]

Genitourinary

Class I antiarrhythmic agents such as flecainide have local anesthetic and anticholinergic properties which may rarely cause urinary retention.[Ref]

Genitourinary side effects including complaints of impotence are reported in 4% of patients. A case of urinary retention associated with flecainide has been reported.[Ref]

Respiratory

A case of reversible flecainide-induced pneumonitis was reported in a 61-year-old man with a remote history of pulmonary tuberculosis. A complete infectious disease work-up was negative. Serial bronchial-alveolar lavages and chest radiographs were consistent with a drug-induced process.[Ref]

Respiratory side effects are extremely rare.[Ref]

Hematologic

One patient developed leukopenia after 5 months of flecainide therapy. The leukopenia resolved after drug discontinuation and did not recur when flecainide was reinstituted. The leukopenia may have been due to a concurrent viral infection.[Ref]

Hematologic side effects are extremely rare.[Ref]

Hepatic

Hepatic side effects including enzyme concentration elevations have been reported in rare cases.[Ref]

Psychiatric

Psychiatric side effects including paranoid psychosis was reported in a 62-year-old patient receiving flecainide for the treatment of malignant neuropathic pain.[Ref]

References

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2. Tjandra-Maga TB, Verbesselt R, Van Hecken A, Mullie A, De Schepper PJ. Flecainide: single and multiple oral dose kinetics, absolute bioavailability and effect of food and antacid in man. Br J Clin Pharmacol. 1986;22:309-16.

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10. Cockrell JL, Scheinman MM, Titus C, et al. Safety and efficacy of oral flecainide therapy in patients with atrioventricular re-entrant tachycardia. Ann Intern Med. 1991;114:189-94.

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13. Clementy J, Dulhoste MN, Laiter C, et al. Flecainide acetate in the prevention of paroxysmal atrial fibrillation: a nine-month follow-up of more than 500 patients. Am J Cardiol. 1992;70:a44-9.

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22. Epstein AE, Hallstrom AP, Rogers WJ, Liebson PR, Seals AA, Anderson JL, Cohen JD, Capone RJ, Wyse DG. Mortality following ventricular arrhythmia suppression by encainide, flecainide, and moricizine after myocardial infarction - the original design concept of the cardiac arrhythmia suppression trial (cast). JAMA. 1993;270:2451-5.

23. Said SAM, Somer ST, Luttikhuis HAO. Flecainide-induced JT prolongation, t wave inversion and ventricular tachycardia during treatment for symptomatic atrial fibrillation. Int J Cardiol. 1994;44:285-7.

24. Roden DM. Risks and benefits of antiarrhythmic therapy. N Engl J Med. 1994;331:785-91.

25. Anderson JL, Platt ML, Guarnieri T, Fox TL, Maser MJ, Pritchett ELC, Kay GN, Plumb VJ, Epstein AE, Bubien RS, Bhandari. Flecainide acetate far paroxysmal supraventricular tachyarrhythmias. Am J Cardiol. 1994;74:578-84.

26. Strambabadiale M, Lazzarotti M, Facchini M, Schwartz PJ. Malignant arrhythmias and acute myocardial ischemia: interaction between flecainide and the autonomic nervous system. Am Heart J. 1994;128:973-82.

27. Donovan KD, Power BM, Hockings BEF, Dobb G, Lee KY. Intravenous flecainide versus amiodarone for recent-onset atrial fibrillation. Am J Cardiol. 1995;75:693-7.

28. Chimienti M, Cullen MT, Casadei G. Safety of long-term flecainide and propafenone in the management of patients with symptomatic paroxysmal atrial fibrillation: report from the flecainide and propafenone italian study investigators. Am J Cardiol. 1996;77:a60-5.

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30. Hopson JR, Buxton AE, Rinkenberger RL, Nademanee K, Heilman JM, Kienzle MG. Safety and utility of flecainide acetate in the routine care of patients with supraventricular tachyarrhythmias: results of a multicenter trial. Am J Cardiol. 1996;77:a72-82.

31. Heisler BE, Ferrier GR. Proarrhythmic actions of flecainide in an isolated tissue model of ischemia and reperfusion. J Pharmacol Exp Ther. 1996;279:317-24.

32. Psaty BM, Psaty SE. Flecainide toxicity in an older adult. J Am Geriatr Soc. 2009;57:751-3.

33. Ramhamadany E, Mackenzie S, Ramsdale DR. Dysarthria and visual hallucinations due to flecainide toxicity. Postgrad Med J. 1986;62:61-2.

34. Moller HU, Thygesen K, Kruit PJ. Corneal deposits associated with flecainide. BMJ. 1991;302:506-7.

35. Ferrick KJ, Power M. Profound exacerbation of neuromuscular weakness by flecainide. Am Heart J. 1990;119:414-5.

36. Pedersen KE, Christiansen BD, Kjaer K, Klitgaard NA, Nielsen-Kudsk F. Verapamil-induced changes in digoxin kinetics and intraerythrocytic sodium concentration. Clin Pharmacol Ther. 1983;34:8-13.

37. Hellestrand KJ. Efficacy and safety of long-term oral flecainide acetate in patients with responsive supraventricular tachycardia. Am J Cardiol. 1996;77:a83-8.

38. Malesker MA, Sojka SG, Fagan NL. Flecainide-induced neuropathy. Ann Pharmacother. 2005;39:1580-1.

39. Ziegelbaum M, Lever H. Acute urinary retention associated with flecainide. Cleve Clin J Med. 1990;57:86-7.

40. Akoun GM, Cadranel JL, Israel-Biet D, Gauthier-Rahman S. Flecainide-associated pneumonitis. Lancet. 1991;337:49.

41. Product Information. Tambocor (flecainide). 3M Pharmaceuticals. 2001;PROD.

42. Bennett MI. Paranoid psychosis due to flecainide toxicity in malignant neuropathic pain. Pain. 1997;70:93-4.

Further information

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Some side effects may not be reported. You may report them to the FDA.

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