Olmesartan with amlodipine and hydrochlorothiazide

How it works

Olmesartan blocks the angiotensin-II type-1 receptor, amlodipine relaxes arterial smooth muscle by blocking L-type calcium channels, and hydrochlorothiazide promotes renal sodium and water loss, giving three complementary blood-pressure-lowering actions.

Prescribing in practice

• Avoid in pregnancy because the angiotensin-receptor-blocker component is foetotoxic, and use only as substitution therapy once the dose of each component is established rather than for initiation.
• The thiazide adds risks of hyponatraemia, hypokalaemia and other electrolyte disturbance, gout and dehydration, which can compound the hypotension and renal effects of the renin-angiotensin blocker.
• Olmesartan has been linked to a rare sprue-like enteropathy, and amlodipine commonly causes ankle oedema; monitor for hyperkalaemia balanced against thiazide-induced potassium loss.

Monitoring

Monitor blood pressure, renal function and serum electrolytes including sodium and potassium after starting and after any change, with closer review in the elderly.

Counselling the patient

• Take this once daily as directed; it replaces taking the three medicines separately.
• Report persistent diarrhoea, severe dizziness, muscle cramps or weakness.
• Tell your doctor immediately if you become pregnant.

Evidence & guidelines

Stepwise addition of a thiazide-type diuretic to a renin-angiotensin blocker plus calcium-channel blocker reflects NICE hypertension step-3 management, with fixed-dose triple therapy aiding adherence.