Flecainide is almost completely absorbed from the gastrointestinal tract following oral administration, with peak plasma concentrations occuring after about three hours. Flecainide is metabolised by the liver but about 40% of a dose is excreted unchanged. Metabolites have little or no antiarrhythmic effect. Flecainide may accumulate in patients with renal failure. Monitoring of concentrations in such patients is therefore important.
