Bendroflumethiazide

How it works

It inhibits sodium-chloride reabsorption at the distal convoluted tubule, promoting natriuresis and diuresis, with a vasodilatory contribution to its long-term antihypertensive effect.

Prescribing in practice

• Older patients are especially prone to hyponatraemia, hypokalaemia and volume depletion, which can cause confusion, falls and acute kidney injury, so use the lowest effective dose and monitor electrolytes.
• It can precipitate or worsen gout, hyperglycaemia and hypercalcaemia, and raise lipids.
• Combine cautiously with other drugs affecting sodium, potassium or renal perfusion, including other diuretics, ACE inhibitors and NSAIDs.

Monitoring

Monitor renal function and electrolytes (notably sodium and potassium) shortly after starting or changing dose and periodically thereafter.

Counselling the patient

• Take it in the morning to avoid disturbed sleep from passing urine.
• Report dizziness, marked weakness, confusion or muscle cramps.
• During acute illness with vomiting or diarrhoea, seek advice as the medicine may need pausing.

Evidence & guidelines

Thiazide-type diuretics have established outcome benefit in hypertension trials and feature in NICE hypertension guidance, with cautious use advised in frail older people.