rapidly acting antihypertensive agent thought to directly act on peripheral arterioles primarily
increases renal and cerebral blood flow, increases plasma renin activity and causes sodium and water retention
reflex tachycardia usually occurswhich may limit its antihypertensive effect and thus an additional agent to block this (eg. beta adrenergic blockers) can provide further efficacy.
plasma half life 3-7hrs
duration of action post-dose 3-8hrs
primarily metabolised by acetylation in the liver, with metabolites excreted in the kidneys
slow acetylator phenotypes (50% of Caucasians and 20% of Asians) are at risk of toxicity with usual dosing