Captopril is an angiotensin-converting enzyme (ACE) inhibitor which reduces peripheral resistance and lowers blood pressure. ACE inhibitors are antihypertensive drugs that act as vasodilators and reduce peripheral resistance. The pharmacological actions of ACE inhibitors are thought to be primarily due to the inhibition of the renin-angiotensin-aldosterone system. ACE inhibitors produce a reduction in both preload and afterload in patients with heart failure. They also reduce left ventricular remodelling. Normally, renal blood flow is increased without a change in glomerular filtration rate.
About 60 to 75% of a dose of Captopril is absorbed from the gastro-intestinal tract and peak plasma concentrations are achieved within about an hour. Absorption has been reported to be reduced in the presence of food. Captopril is about 30% bound to plasma proteins. It crosses the placenta and is found in breast milk at about 1% of maternal blood concentrations. It is largely excreted in the urine, 40 to 50% as unchanged drug, the rest as disulfide and other metabolites. The elimination half-life has been reported to be 2 to 3 hours but this is increased in renal failure. Captopril is removed by haemodialysis.
Captocos® tablets are used in the management of hypertension, in heart failure, following myocardial infarction and in diabetic nephropathy.