A sulfonamide that is N-phenylmethanesulfonamide in which the phenyl group is substituted at position 4 by a 1-hydroxy-2-(isopropylamino)ethyl group. It has both beta-adrenoreceptor blocking (Vaughan Williams Class II) and cardiac action potential duration prolongation (Vaughan Williams Class III) antiarrhythmic properties. It is used (usually as the hydrochloride salt) for the management of ventricular and supraventricular arrhythmias.