Propafenone

Propafenone is a drug from the heterogeneous group of Class Ic antiarrhythmics. Its average half-life is about 6.0 hours.

Like all class I antiarrhythmics, propafenone binds to cardiac sodium channels (sodium channel antagonist). Its protein binding capacity is over 90%. Due to its comparatively long binding time, propafenone is also effective at rest.

Propafenone blocks the influx of sodium ions into the heart muscle cells, thus calming and normalising muscle excitation. At the same time, propafenone also has a slightly pronounced effect as a beta-blocker. Propafenone reduces the rate of increase of the action potential and thus slows down the excitation conduction (negative dromotropic effect). The refractory periods in the atrium, AV node and ventricles are delayed. In patients with Wolff-Parkinson-White syndrome (WPW syndrome), propafenone prolongs the refractory times of the accessory pathways and thus normalizes the heart rhythm.

The main areas of application are supraventricular tachycardias such as atrial fibrillation, ventricular tachycardias including ventricular fibrillation and tachyarrhythmias.

There is insufficient experience with its use in pregnant and breastfeeding women. Animal experiments have not shown any harm to the offspring at therapeutic doses. However, since propafenone hydrochloride is transferred to the unborn child and excreted into the breast milk, the drug should only be used during pregnancy or lactation on the doctor's express instructions.

Circulatory regulation disorders: Frequent; circulatory regulation disorders with a tendency to an orthostasis syndrome. These orthostatic problems occur particularly in older patients with limited myocardial performance. Dizziness, syncope, chest pain.

Cardiac arrhythmias: The proarrhythmic effects are also manifested either as bradycardias, conduction disorders (e.g. sinuatrial, atrioventricular or intraventricular block) or as an acceleration of the heartbeat sequence (e.g. recurrence of ventricular tachycardia). Heart failure may worsen. Ventricular flutter or fibrillation may occur rarely.

Gastrointestinal tract: Common; loss of appetite, nausea, nausea, feeling of fullness, constipation. Dry mouth, bitter taste and numbness in the mouth, especially at higher initial doses.

General: Frequently; fever reactions.

Liver and bile: Occasional; intrahepatic cholestasis as an expression of a hyperergic-allergic reaction and/or increase of liver-specific enzymes such as serum transaminases, alkaline phosphatase, possibly in combination with an icterus and toxic hepatitis.

Breast and reproductive organs: Rarely: decrease in potency and in the number of spermatozoa (after high doses of propafenone, which regressed after discontinuation of treatment.

Respiratory tract: Occasional; breathing difficulties in patients with a tendency to bronchospasm.

Skin and mucous membranes: Occasional; allergic skin symptoms (e.g. redness, itching, inflammatory rash (exanthema), hives (urticaria)).

Immunophenomena: Rare; increase of antinuclear antibodies (ANA), occurrence of lupus erythematosus-like syndrome.

Blood and lymphatic system: Rare; decrease in leukocyte or granulocyte or platelet counts in the blood, which were reversible after discontinuing cuxafenone 300 mg. Agranulocytosis

Psychogenic effects: Common; Anorexia. Occasionally; fatigue, mental disorders such as anxiety and confusion, restlessness, nightmares and sleep disorders.

Eyes: Frequently; vision disorders.

CNS: Frequently: Sensory disturbances (paresthesia); Occasionally; disturbances of involuntary movements; ataxias. Very rare are cramp-like symptoms of overdose.

Skin: Rarely exanthema has been reported. Furthermore described a pustulosis acuta generalisata (Conforti C et al. 2020)

Rytmonorm®

Cuxafenone®

Because propafenone is structurally related to beta-blockers, it also has lidocaine and quinidine-like effects and can also block calcium and beta channels. Docking to ATP-sensitive potassium channels in heart muscle cells is considered undesirable.

The following frequency data are used to evaluate side effects:

• Very frequent: more than 1 treated person out of 10
• Often: 1 to 10 treated from 100
• Occasionally: 1 to 10 treated from 1.000
• Rare: 1 to 10 treated from 10.000

• Very rare: less than 1 treated person per 10.000

1. Conforti C et al (2020) Acute generalized exanthematous pustulosis caused by propafenone: An emerging skin adverse reaction. Dermatol Ther e1: 3595.
2. Veale D et al (1990) Propafenone. Lancet 335:979.