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Angiotensin mediates its effects through two receptors. The AT-1 receptor mediates
the vasoconstrictive and aldosterone stimulating effects of angiotensin II. The
action of angiotensin II at the AT-2 receptor tends to antagonize the pressor
effects of the AT-1 receptor.
- angiotensin Receptor Blockers (ARB)
specifically block the action of angiotensin II at the AT-1 receptor.
the antihypertensive efficacy of ARBs (e.g. Losartan) appears to be equal to that
of atenolol or ACE inhibitors; ARBs and thiazide diuretics may be combined, resulting
in additive hypotensive effects. The combination of an ACE inhibitor and an angiotensin
II receptor antagonist is unlikely to have an additive effect.
- there is
a lower incidence of cough in patients taking ARBS as compared to patients taking
- owing to their receptor selectivity for the AT-1 receptor,
and their lack of potentiation of bradykinin and possibly other vasoactive peptides,
cough and angio-oedema are much less likely to occur than with ACE inhibitors
- there is evidence that ARBs are renoprotective in patients
with type 2 diabetes mellitus and nephropathy. This effect was beyond that attributable
to blood pressure control (2,3)
It had been stated that the clearest indication for use of angiotensin-II-receptor
antagonists was in patients among whom coughing has limited the use of ACE inhibitors,
but for whom blockade of the renin-angiotensin system offers particular benefit
(5). However the British Hypertension Society have included both ARBs and ACE
inhibitors in the step 1 of their A/CD guideline of blood pressure management
Effectivity of ARB if intolerant of ACE inhibitor in reduction of cardiovascular
- ACE inhibitors reduce major cardiovascular events, but are not tolerated
by about 20% of patients
- a study (TRANSCEND) assessed whether the angiotensin-receptor blocker
telmisartan would be effective in patients intolerant to ACE inhibitors
with cardiovascular disease or diabetes with end-organ damage
- there was no significant benefit with respect to the study primary outcome
(composite of cardiovascular death, myocardial infarction, stroke, or
hospitalisation for heart failure) in the ARB treated group
of product characteristics should be consulted before prescribing specific angiotensin
II receptor antagonists.
- 1. Drug and Therapeutics Bulletin (1995). Losartan - a new antihypertensive.
Williams B, Poulter NR, Brown MJ, Davis M, McInnes GT, Potter JF, et al. Guidelines
for management of hypertension: report of the fourth working party of the
British Hypertension Society, 2004?BHS IV. J Hum Hypertens 2004;18: 139-85
- 3. Ichiki, T. et al. (1995). Effects on blood pressure and exploratory
behaviour of mice lacking angiotensin II type 2 receptor. Nature, 377, 748-50.
Brenner BM et al, for the RENAAL Study Investigators (2001). Effects of losartan
on renal and cardiovascular outcomes in patients with type 2 diabetes and
nephropathy. N Engl J Med, 345, 861-9.
- 5. Prescribers' Journal (1999), 39 (1), 24-30.
Telmisartan Randomised AssessmeNt Study in ACE iNtolerant subjects with cardiovascular
Disease (TRANSCEND) Investigators. Effects of the angiotensin-receptor blocker
telmisartan on cardiovascular events in high-risk patients intolerant to angiotensin-converting
enzyme inhibitors: a randomised controlled trial. Lancet. 2008 Sep 27;372(9644):1174-83
Last reviewed 01/2018