These drugs all end in –pril. Examples are lisinopril, ramipril, perindopril and enalapril. The dose range for lisinopril in hypertension is 5–40 mg once daily. The ACE inhibitors block the conversion of angiotensin 1 to angiotensin II by inhibiting angiotensin converting enzyme. Angiotensin II is a powerful vasoconstrictor and in this way blood pressure is thought to be lowered. ACE inhibitors have antiproteinuric properties and are specifically indicated in patients with proteinuric nephropathy (urine PCR >50 mg/mmol). The commonest side effect of an ACE inhibitor is a dry cough, the occurrence of which should prompt a switch to an angiotensin receptor blocker. We have already alluded to the fact that ACE inhibitors may worsen renal function in patients with bilateral renovascular disease and also cause hyperkalaemia. This is in addition to an acute worsening of renal function if the patient becomes intravascularly deplete. Patients prescribed an ACE inhibitor must be advised to omit this drug and seek help from their general practitioner if they start vomiting or develop diarrhoea in order to reduce the risk of drug induced AKI.

These drugs all end in –sartan. Examples are losartan, irbesartan and valsartan. The dose range for losartan in hypertension is 25–100 mg daily in 1 or 2 divided doses. ARBs lower blood pressure by blocking the receptor to which angiotensin II binds, but do not cause cough. They share an antiproteinuric effect with ACE inhibitors and are also as likely to cause hyperkalaemia, worsen renal function in patients with bilateral renovascular disease and AKI in the context of dehydration. ARBs should not be combined with ACE inhibitors as this may result in more adverse events without any added clinical benefit.

Calcium channel blockers are vasodilators. There are two types: dihydropyridines such as amlodipine and nifedipine which do not lower heart rate, and rate-limiting calcium channel blockers diltiazem and verapamil which do. Amlodipine 5–10 mg once daily is the most commonly prescribed dihydropyridine calcium channel blocker. It is generally well tolerated, is easy to combine with other drugs but can cause troublesome ankle swelling. It is important to avoid co-prescribing a rate limiting calcium channel blocker with a beta blocker, out-with exceptional circumstances, as this can lead to profound bradycardia.

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