Chapter: Basic & Clinical Pharmacology : Agents Used in Cardiac Arrhythmias

Flecainide (Subgroup 1C)

Flecainide is a potent blocker of sodium and potassium channels with slow unblocking kinetics.

FLECAINIDE (SUBGROUP 1C)

Flecainide is a potent blocker of sodium and potassium channels with slow unblocking kinetics. (Note that although it does block certain potassium channels, it does not prolong the action poten-tial or the QT interval.) It is currently used for patients with otherwise normal hearts who have supraventricular arrhythmias. It has no antimuscarinic effects.

Flecainide is very effective in suppressing premature ventricular contractions. However, it may cause severe exacerbation of arrhythmia even when normal doses are administered to patients with preexisting ventricular tachyarrhythmias and those with a previous myocardial infarction and ventricular ectopy. This was dramatically demonstrated in the Cardiac Arrhythmia Suppression Trial (CAST), which was terminated prematurely because of a two and one-half-fold increase in mortality rate in the patients receiv-ing flecainide and similar group 1C drugs. Flecainide is well absorbed and has a half-life of approximately 20 hours. Elimination is both by hepatic metabolism and by the kidney. The usual dos-age of flecainide is 100–200 mg twice a day.

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Basic & Clinical Pharmacology : Agents Used in Cardiac Arrhythmias : Flecainide (Subgroup 1C) |