Olmesartan with amlodipine

How it works

Olmesartan blocks the angiotensin-II type-1 receptor to reduce vasoconstriction and aldosterone-driven sodium retention, while amlodipine inhibits vascular L-type calcium channels to relax arterial smooth muscle; the two lower blood pressure by complementary mechanisms.

Prescribing in practice

• Avoid in pregnancy because the angiotensin-receptor-blocker component is foetotoxic; counsel women of childbearing potential and stop promptly if pregnancy is planned or confirmed.
• Olmesartan has been associated with a rare severe sprue-like enteropathy presenting as chronic diarrhoea and weight loss, which resolves on withdrawal; consider this in unexplained chronic diarrhoea.
• Amlodipine commonly causes dose-related ankle oedema and flushing, and the combination can cause symptomatic hypotension and hyperkalaemia, particularly in volume depletion or renal impairment.

Monitoring

Monitor blood pressure, renal function and serum potassium after initiation and following any dose change.

Counselling the patient

• Report any persistent severe diarrhoea or unexplained weight loss to your doctor.
• Ankle swelling and flushing are common and relate to the amlodipine component.
• Tell your prescriber straight away if you become pregnant or plan to.

Evidence & guidelines

Combining a renin-angiotensin blocker with a calcium-channel blocker is supported by NICE hypertension guidance as a rational step-up, and fixed-dose combinations improve adherence.