Bretylium (also bretylium tosylate) is an antiarrhythmic agent. It blocks the release of noradrenaline from nerve terminals. In effect, it decreases output from the peripheral sympathetic nervous system. It also acts by blocking K+ channels and is considered a class III antiarrhythmic. The dose is 5-10 mg/kg and side effects are hypertension followed by hypotension and ventricular ectopy.