Pharmacology of ACE inhibitors

How angiotensin converting enzyme inhibitors works / pharmacology of ACE inhibitors/angiotensin converting enzyme inhibitors.

ANGIOTENSIN CONVERTING ENZYME INHIBITORS

Angiotensin converting enzyme inhibitors are used as Antihypertensive drugs.
• they inhibit generation of angiotensin II, which is a potent vasoconstrictor.
• they inhibit the degradation of bradykinin, which is potent vasodilator.
• they stimulate the synthesis of vasodilating PGs through bradykinin.
• reduce sympathetic nervous system activity.

MECHANISM OF ACTION

▪ACE inhibitors also reduce aldosterone production hence sodium and water rentention.

▪They dilate both arteries as well as veins, hence they reduce afterload and preload.

▪All these actions contribute to their Antihypertensive effect.

PHARMACOKINETICS

▪ ACE inhibitors are usually given orally.
▪ In emergency, enalapril can be given intravenously.
▪ Food reduces absorption of captopril hence it should be given 1 hour before meals.
▪ They poorly cross the BBB.
▪ Metabolized in liver and excreted in urine.

ADVERSE EFFECT 

1.Cough
2.Angioedema.
3.Proteinuria.
4.Taste alteration.
5.Teratogenic effect.
6.Severe hypotension may occur 1-2 hour after taking first dose.
7.Neutropenia.
8.Rashes.
9.Itching.
10.Loss of appetite, nausea, vomiting, diarrhoea.

USES OF ACE INHIBITORS

 
1 Hypertension : use of ACE inhibitors reduces the incidence of heart disease in hypertensive patient. ACE inhibitors are useful in all grades of hypertension.

2 Congestive cardiac failure : ACE inhibitors should be prescribed to all patients with inpaired left ventricular function.

3 Myocardial infarction : ACE inhibitors should be started within 24 hours in patients with MI.

4 Diabetic nephropathy : ACE inhibitors are preferred in diabetic nephropathy as they control both systemic hypertension and intraglomerular pressure.

5 Scleroderma renal crisis : ACE inhibitors produce dramatic improvement in patients with renal crisis and accerelated hypertension.