Pharmacology · Class
Thiazide and thiazide-like diuretics !
Moderate diuretics that block salt reabsorption in the distal tubule. First-line medicines for high blood pressure.
Updated 2026-11-01
What they are
Diuretics that inhibit the Na⁺-Cl⁻ cotransporter (NCC) of the distal convoluted tubule. Thiazides (hydrochlorothiazide, chlorothiazide) and thiazide-like drugs (chlortalidone, indapamide, metolazone) share the target. They are first-line for hypertension and also treat oedema.
Mechanism of action
Blocking NCC leaves more sodium and chloride in the urine. More sodium reaches the collecting duct, where it is exchanged for potassium and hydrogen, so potassium is lost. In the distal tubule they increase calcium reabsorption, so urinary calcium falls.
Target: Na⁺-Cl⁻ cotransporter (NCC)
Drugs in this class
- HydrochlorothiazideA thiazide diuretic, one of the first-line medicines for high blood pressure. It blocks salt reabsorption in the…Na⁺-Cl⁻ cotransporter (NCC) of the distal convoluted tubule
- ChlortalidoneA long-acting thiazide-like diuretic for high blood pressure and oedema. Its effect lasts more than a day.Na⁺-Cl⁻ cotransporter (NCC) of the distal convoluted tubule
- IndapamideA thiazide-like diuretic used mainly for high blood pressure. It lowers vascular resistance with little effect on…Na⁺-Cl⁻ cotransporter (NCC) of the distal convoluted tubule
- MetolazoneA thiazide-like diuretic often added to a loop diuretic when oedema resists treatment. The pair can cause very large…Na⁺-Cl⁻ cotransporter (NCC) of the distal convoluted tubule
- ChlorothiazideThe first thiazide diuretic, available by mouth and as an IV injection. Used as an adjunct for oedema and in high…Na⁺-Cl⁻ cotransporter (NCC) of the distal convoluted tubule
Others in the class
- Bendroflumethiazide
- Xipamide
Test yourself
Think of the answer, then tap the question to see it.
Which transporter do thiazides block?
The Na⁺-Cl⁻ cotransporter (NCC) on the luminal side of the distal convoluted tubule.
Why can thiazides help prevent calcium kidney stones?
They increase calcium reabsorption in the distal tubule, so less calcium reaches the urine.
Can you name four metabolic effects of thiazides?
Hypokalaemia, hyponatraemia, hyperuricaemia and hyperglycaemia; also hypercalcaemia and higher lipids.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - HYDROCHLOROTHIAZIDE tablet (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - CHLORTHALIDONE tablet (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.