Propafenone versus quinidine slow-release for the treatment of chronic ventricular arrhythmias

The efficacy and side-effects of oral propafenone 300 mg b.i.d. were compared to those of quinidine slow-release 800 mg b.i.d. in a randomized double-blind placebo controlled cross-over study in 12 patients with symptomatic premature ventricular complexes (PVCs). Furthermore during steady-state the plasma levels of propafenone and quinidine were measured repeatedly over an 8-hour period and correlated to the numbers of PVCs. In 6 patients both drugs reduced PVCs by 80%. In 2 patients this effect was obtained by propafenone and not by quinidine, while the reverse was found in another 2 patients. In 2 patients neither of the drugs was able to reduce PVCs by 80%. During treatment with quinidine 4 patients experienced diarrhoea and 1 patient suffered headaches taking propafenone. The plasma levels showed great variation. No correlation between the plasma levels expressed as area under the concentration-time curve and the reduction of PVCs was found.