Bretylium (bretylium tosylate) is an antifibrillatory and antiarrhythmic agent. Bretylium is abromobenzyl quaternary ammonium compound which selectively accumulates in sympathetic ganglia and their postganglionic adrenergic neurons where it inhibits norepinephrine release by depressing adrenergic nerve terminal excitability. The drug has a direct positive inotropic effect on the myocardium and blocking effect on postganglionic sympathetic nerve transmission. The drug is poorly absorbed orally, requiring either i.m. or i.v. administration.