Effect of propafenone hydrochloride on lymphocyte membrane beta 2 adrenoceptors in ventricular arrhythmias

Propafenone (2-[3 propylamino-2 hydroxy-propoxy] 3 phenyl propiophenone hydrochloride) is a new and potent class I (Vaughan Williams classification) antiarrhythmic drug. Among its multiple electrophysiologic properties, propafenone exerts β-antagonist effects that may reflect a structural similarity with β blockers. 1,2 These β-blocking effects have been studied in animals and human beings, but remain controversial. They would correspond to 5 to 40% of propranolol's β-blocking activity, at usual therapeutic doses. 3 A recent study has established the interaction of this drug with both β 1 and β 2 adrenoceptors. 4 Because nonselective β blockers without intrinsic sympathomimetic activity tend to “up-regulate” membrane β-adrenoceptor density, 5 we studied the lymphocytic β-adrenoceptor changes after an oral treatment with propafenone in patients with ventricular arrhythmias.