Angiotensin converting enzyme inhibitors and angiotensin receptor blockers in hypertension

First line antihypertensive drugs are classified as A, B, C, or D.1 Drugs classed as A comprise angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs); B drugs are β adrenoceptor antagonists (also known as β blockers) and have fallen out of favour for use as single agents in patients in whom uncomplicated essential hypertension is the sole indication for drug treatment; C drugs are calcium antagonists; and D drugs are diuretics. This mnemonic can usefully guide initial treatment (see box 1) as well as addition of a second agent when needed2 and is used in the National Institute for Health and Clinical Excellence (NICE) guideline on management of hypertension in adults in primary care.3 Randomised controlled trial data show that untreated patients with essential hypertension with normal or raised plasma renin concentration (for example, many younger patients with essential hypertension, especially those who have successfully reduced their dietary salt intake) respond rather better to A and B drugs, whereas those with low renin (such as people of African origin and older patients) respond well to C or D drugs).1 The table⇓ summarises the advantages and disadvantages of the main classes of drugs used to start treatment of hypertension.