[Interactions of quinidine and propranolol with mexiletine, encainide, flecainide and tocainide].

Blood serum quinidine sulphate and propranolol levels have been measured in patients with cardiac arrhythmias treated simultaneously with mexiletine, flecainide, encainide and tocainide. It was found that mexiletine and encainide increase quinidine sulphate serum concentrations. Propranolol serum concentrations have been increased by mexiletine, encainide flecainide, and tocainide. Flecainide ant tocainide have not changed quinidine sulphate serum concentrations.