Enalapril with hydrochlorothiazide

How it works

Enalapril blocks angiotensin-converting enzyme to reduce angiotensin II and aldosterone, causing vasodilatation, while hydrochlorothiazide promotes renal sodium and water excretion; the combination gives complementary blood-pressure lowering and the ACE inhibitor offsets thiazide-induced potassium loss.

Prescribing in practice

• Both components are contraindicated in pregnancy, and ACE inhibitors carry a risk of angioedema, so the combination must be avoided in women who are or may become pregnant.
• The two drugs have opposing effects on potassium and the thiazide can disturb sodium, magnesium, urate and glucose, so electrolytes and renal function must be checked, particularly with concurrent renin-angiotensin or potassium-affecting drugs.
• Risk of first-dose and volume-related hypotension and of acute kidney injury, especially in volume-depleted patients or those also taking NSAIDs (the "triple whammy").

Monitoring

Check renal function and electrolytes before starting and after initiation or dose change, alongside regular blood pressure review.

Counselling the patient

• Stop the tablet and seek urgent help if you notice swelling of the face, lips, tongue or throat.
• Tell us straight away if you become pregnant or are planning pregnancy.
• A dry cough or dizziness on standing can occur; report persistent symptoms.

Evidence & guidelines

Fixed-dose ACE inhibitor with thiazide combinations are well established for hypertension where single-tablet therapy aids adherence.