Class 1C antiarrhythmic indicated to prolong time to recurrence of symptomatic paroxysmal atrial fibrillation/flutter and paroxysmal supraventricular tachycardia in patients without structural heart disease, and for treatment of documented life-threatening ventricular arrhythmias.
Also known as: Rytmonorm
DailyMed approved label (Propafenone Hydrochloride Extended-Release Capsule; setID 2ecd6452-ccc3-493f-9a4a-69f0fbf67a42).
DailyMed approved label (Propafenone Hydrochloride Extended-Release Capsule; setID 2ecd6452-ccc3-493f-9a4a-69f0fbf67a42).
Propafenone raises digoxin levels, potentiating digitalis toxicity.
Propafenone raises digoxin concentrations (inhibition of efflux transport, with documented 30–80% increases) and, as a class 1C antiarrhythmic, has conduction-depressant effects that add to those of digoxin (AV block risk). The combination is common in atrial fibrillation. Monitor digoxin levels when propafenone is started (reducing the digoxin dose if needed), watch the ECG (PR, QRS, rate) and symptoms of toxicity of both drugs.
Propafenone can raise digoxin levels and both depress AV conduction. Monitor digoxin levels, ECG and toxicity signs.
Propafenone reduces digoxin renal clearance; largest effect at high doses.
Digoxin levels, bradycardia, GI symptoms.
Arrhythmia, nausea, confusion or lethargy.
Consider digoxin reduction and monitor levels/ECG.
DailyMed (FDA) — approved Propafenone label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2ecd6452-ccc3-493f-9a4a-69f0fbf67a42 ; approved Digoxin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e61d2108-d871-44c0-b12a-2e61fbb56967 — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Grapefruit juice increases propafenone bioavailability by inhibiting intestinal CYP3A4 and P-glycoprotein, raising the risk of cardiac adverse effects.
Avoid grapefruit juice during treatment; the risk is greater in poor CYP2D6 metabolisers.
EMC-UK (MHRA) — approved Propafenone SmPC: https://www.medicines.org.uk/emc/product/1733/smpc
Propafenone is contraindicated in structural heart disease or ventricular dysfunction because of the risk of proarrhythmia.
Do not use in structural heart disease or left ventricular dysfunction.
EMC-UK (MHRA) — approved Propafenone SmPC: https://www.medicines.org.uk/emc/product/1733/smpc
Propafenone crosses the placenta; data in pregnancy are limited and have not shown clear teratogenicity.
Use only if the maternal benefit outweighs the fetal risk.
Propafenone is excreted into breast milk; prefer an alternative in at-risk infants.
Document the decision to treat women of childbearing age; consider contraception if therapy is new.
EMC-UK (MHRA) — approved Propafenone SmPC: https://www.medicines.org.uk/emc/product/1733/smpc
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Class 1C antiarrhythmic: reduces the upstroke velocity (Phase 0) of the monophasic action potential, prolongs the effective refractory period, increases the diastolic excitability threshold and reduces spontaneous automaticity; beta-blocking activity ~1/40 that of propranolol per mg.
Blockade of fast myocardial sodium channels (membrane-stabilizing action) with local anesthetic effect; reduced fast sodium inward current in Purkinje and myocardial fibers decreases conduction and excitability.
Almost completely absorbed orally, with plasma peaks ~3.5 h; dose-dependent absolute bioavailability (3.4% with 150 mg; 10.6% with 300 mg; up to 21.4% with solution); protein binding > 95%.
Extensive saturable first-pass metabolism: in > 90% of patients (CYP2D6 extensive metabolizers) it forms 5-hydroxypropafenone (active) and N-depropylpropafenone (CYP3A4/CYP1A2); in poor metabolizers half-life is longer and levels 1.5–5x higher.
Elimination half-life of 2–10 h in CYP2D6 extensive metabolizers and 10–32 h in poor metabolizers.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
