Introduction

Angiotensin II Receptor Blockers (ARBs) are usually used in hypertension, HF and post-MI, usually when an ACE-inhibitor has been ineffective or not tolerated. They are also used ot treat diabetic nephropathy.

ACE-Inhibitors often result in a dry cough (approx. 20% of patients), probably caused by the accumulation of bradykinin secondary to the reduced action of ACE. Patients unable to tolerate the cough should be treated with the second line ARBs.

Sometimes called ‘Sartans’ – all Angiotensin II Receptor Blockers end with ‘sartan’, e.g. Losartan.

Mechanism of action

• Selectively inhibit angiotensin II at the AT₁ receptor site
• Binding of angiotensin II at the AT₁ receptor causes: vasoconstriction, release of aldosterone, sympathetic activation and other potentially harmful effects in the CV system. Therefore, by antagonising angiotensin II at the AT₁ receptor it will prevent these effects
• Therefore, causes VASODILATION and blockage of aldosterone release

Contra-Indications

• Patients on an ARBs with aliskiren is contra-indicated if their eGFR is below 60ml/min/1.73 m²
• Combination of ARBs with aliskiren is contra-indicated in diabetes mellitus

Cautions

• Afro- Caribbean patients with LV hypertrophy, may not benefit from ARBs
• Aortic/Mitral stenosis
• Elderly, (initially start with low appropriate doses)
• Hypertrophic cardiomyopathy
• History of angioedema
• 1^o aldosteronism (may not benefits from ARBs)
• Renal artery stenosis

Interactions

The interactions listed here are POTENTIALLY SERIOUS which is indicated by a black dot in the BNF. Further details of these interactions can be found in the BNF or Stockleys.

Furthermore, there are other interaction which are not potentially serious, nevertheless they should still be monitored and clinical judgement should be used.

• ACE-Inhibitors
• Aliskiren
• Ciclosporin
• Diuretics
• Potassium sparing diuretics and aldosterone antagonists
• Lithium
• Potassium slats

Hyperkalaemia, angioedema (possible delayed onset), symptomatic hypotension which includes dizziness (especially in patients with intravascular volume depletion, e.g. patients taking high dose diuretics)

Pregnancy

• Unless it is essential, ARBS should be AVOIDED in pregnancy
• It may potentially be teratogenic. Therefore, may affects the foetal and neonatal blood pressure control and renal function
• Neonatal skulls defects and oligohydramnios (too little amniotic fluid) have been reported.

Breast feeding

• Limited data on ARBs in breast feeding
• Generally not recommended in breast feeding
• Other alternatives should be used, which have more data on their safety in breast feeding

Renal Impairment

• Use with caution
• Start with a low dose, adjust dose according to response

Monitoring

• Monitor plasma K⁺ concentration, especially in elderly and in patient with renal impairment. Can lead to Hyperkalaemia

References

• BNF 70, Joint Formulary Committee (2015) British National Formulary. 70th Ed., London: British Medical Association and Royal Pharmaceutical Society of Great Britain.
• Payne, J and Willacy, H. (2016). Oligohydramnios
• British Hypertension Society. (2008). Angiotensin Receptor Blockers (ARBs)

Related Articles

• ACE Inhibitors
• Amiodarone
• Beta Blockers
• Calcium Channel Blockers
• Digoxin