Characterization of a new oral antiarrhythmic drug, flecainide (R818)

Fleckcainide is a local anaesthetic with five times the potency of procaine on frog nerve, with a longer duration of action, and reduces the maximum rate of depolarisation in cardiac muscle at low concentration.

Abstract

Flecainide is a local anaesthetic with five times the potency of procaine on frog nerve, with a longer duration of action. It reduces the maximum rate of depolarisation in cardiac muscle at low concentration, both in solutions containing 5.6 mM KCl and 2.8 mM KCl. It has no anti-sympathetic effects, nor does it antagonise the positive inotropic action of calcium on cardiac muscle. Flecainide prolonged the duration of the action potential at 90% repolarisation. In guinea-pigs anaesthetised with urethane does of 5 mg/kg of flecainide significantly increased the amount of ouabain necessary to induce heart block and ventricular arrhythmias. Flecainide 15 mg/kg caused abnormal ventricular conduction and death in this preparation, but in pithed rats doses of 30 mg/kg of flecainide caused no abnormalities in the electrocardiogram. Flecainide is a class 1 antiarrhythmic drug, with very little negative inotropic or chronotropic action.