Propranolol in cardiac arrhythmias: a comparative study of the conventional and long-acting formulations.

The comparative anti-arrhythmic effect of equivalent daily doses of conventional propranolol ('Inderal') and long-acting propranolol ('Inderal' LA) was assessed in a double-blind, crossover study lasting 6 weeks in 13 patients with cardiac arrhythmias. Patients were investigated using 24-hour ambulatory monitoring. Both formulations of propranolol significantly reduced the heart rate, together with the number of ventricular premature beats and ventricular couplets, with no significant difference between treatments. The two formulations also produced similar plasma concentrations of propranolol. The long-acting formulation of propranolol proved an effective anti-arrhythmic treatment which, with once-daily dosage, may improve patient compliance with treatment.