Propafenone

Antiarrhythmics
Antiarrhythmics

A class IC antiarrhythmic with mild beta-blocking action, used to keep sinus rhythm in atrial fibrillation in hearts without structural disease.

Updated Nov 1, 2026

Quick facts

Group: Antiarrhythmics
Target: Cardiac sodium channel Nav1.5 (and β-adrenergic receptors)
Used for: Prolonging the time to recurrence
Key effects: Unusual or metallic taste · Nausea · Dizziness
Monitor: ECG before and during treatment
ATC: C01BC03

No doses: the clinician sets them by the current guideline.

Mechanism of action

Cardiac sodium channel Nav1.5 (and β-adrenergic receptors)Propafenone

The figure shows propafenone bound to the rat cardiac sodium channel Nav1.5, very similar to the human channel.

Target in 3D: Cardiac sodium channel Nav1.5 (and β-adrenergic receptors). PDB structure 7FBS (RCSB PDB, public domain). View the structure at RCSB PDB

Propafenone blocks the fast inward sodium current, mainly in Purkinje fibres, slowing the action potential upstroke and conduction (longer PR and QRS). It also has weak beta-blocking activity, which can slow the heart and narrow the airways, and a local anaesthetic effect.

Propafenone blocks the Nav1.5 sodium channel
Conduction slows: longer PR and wider QRS
Weak beta blockade adds slowing of the heart

Indications

Prolonging the time to recurrence of symptomatic paroxysmal or persistent atrial fibrillation, without structural heart disease Atrial fibrillation →
Prolonging the time to recurrence of disabling PSVT, without structural heart disease Supraventricular tachycardia (AVNRT, AVRT) →
Documented life-threatening ventricular arrhythmias Ventricular tachycardia →

Adverse effects

Common

Unusual or metallic taste
Nausea, vomiting and constipation
Dizziness, headache and fatigue
First-degree AV block and QRS widening

Contraindications

Heart failure or cardiogenic shock
Sinoatrial, AV or intraventricular conduction disorders without a pacemaker
Known Brugada syndrome
Bradycardia or marked hypotension
Bronchospastic disorders and severe obstructive lung disease
Marked electrolyte imbalance

Key interactions

CYP2D6 inhibitors combined with CYP3A4 inhibitors: Large rise in propafenone levels and proarrhythmia; the combination is avoided
Digoxin: Higher digoxin levels
Warfarin: Higher warfarin levels; INR is checked
Lidocaine: More central nervous system effects

What is monitored

ECG before and during treatment: PR and QRS
Blood count if infection signs appear
Pacemaker function in patients with devices

Administration and safety

Used only in hearts without structural disease; ECG is taken before starting.
In atrial fibrillation or flutter it is given with a drug that slows the AV node.
Immediate-release and extended-release products are not interchangeable one for one: the product is checked.

Pregnancy and breastfeeding

Human data are limited; it is used in pregnancy only if the benefit justifies the risk to the fetus.

Nursing care

Check pulse and ECG; report QRS widening, fainting or palpitations.
Ask about wheeze or breathlessness in patients with lung disease.
Teach the patient to report fever, sore throat or chills (agranulocytosis).

Pharmacokinetics

Metabolism: Liver, mainly CYP2D6 (also CYP3A4 and CYP1A2); poor CYP2D6 metabolisers reach higher levels
Elimination: Mostly as metabolites; dose is lowered in liver impairment

Test yourself

Think of the answer, then tap the question to see it.

What property distinguishes propafenone from flecainide?

Weak beta-blocking activity, so it can cause bradycardia and bronchospasm.

Which inherited ECG syndrome can propafenone unmask?

Brugada syndrome.

Why do some patients reach much higher propafenone levels?

They are poor CYP2D6 metabolisers or take CYP2D6 and CYP3A4 inhibitors together.

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Connections

← Back to the class: Antiarrhythmics

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - PROPAFENONE HYDROCHLORIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); Propafenone: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); 7FBS: structure of a channel (RCSB Protein Data Bank, 2021).

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Representative model, for educational purposes only.