Thiazide and thiazide-like diuretics
Blocking salt reabsorption in the distal tubule, so more salt and water leave.
Also called thiazides and thiazide-type diuretics.
Class card
- Drugs
- Hydrochlorothiazide, Chlortalidone, Indapamide and Bendroflumethiazide
- Used for
- High blood pressure, as a first-line drug
- Edema from heart, liver or kidney disease
- Known for
- Low potassium (hypokalemia)
- Low sodium (hyponatremia)
- Raised uric acid (hyperuricemia)
- Name stems
- -thiazide, -tizide
5 cards: the class, and each drug in it.
Mechanism of action
How do thiazide and thiazide-like diuretics work?
They block the sodium-chloride cotransporter in the distal convoluted tubule, so more sodium, chloride and water leave in the urine, along with potassium and magnesium, while calcium and uric acid are held back. The lasting fall in blood pressure comes mainly from lower peripheral resistance, by a mechanism that is not fully understood.
The drugs
Thiazide and thiazide-like diuretics with a card
- HydrochlorothiazideIts label also warns of non-melanoma skin cancer, mostly squamous cell carcinoma, seen mainly with large cumulative doses.
- ChlortalidoneChlortalidone is the INN; the US name is chlorthalidone. Its half-life of 40 to 60 hours is much longer than hydrochlorothiazide's.
- IndapamideAn indoline rather than a true thiazide; its label warns most of severe hyponatremia, mostly in older women.
- BendroflumethiazideNot sold in the US, so it has no FDA label; it was formerly called bendrofluazide in the UK.
Uses
What are thiazide and thiazide-like diuretics used for?
- High blood pressure, as a first-line drug
- Edema from heart, liver or kidney disease
Side effects
Side effects of thiazide and thiazide-like diuretics
- Low potassium (hypokalemia)Known forSerious
- Low sodium (hyponatremia)Known forSerious
- Raised uric acid (hyperuricemia)Known for
- Gout attacks
- Raised blood sugar (hyperglycemia)
- Raised cholesterol and triglycerides
- Raised calcium (hypercalcemia)
- Low magnesium (hypomagnesemia)
- Dizziness on standing (orthostatic hypotension)
- Erectile dysfunction
What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.
Watch for
Cautions
- Check potassium and sodium; low potassium makes digoxin toxicity and arrhythmias more likely.
- They cut lithium clearance and can cause lithium toxicity.
- Sulfonamide-derived: contraindicated in anuria and in allergy to sulfonamide drugs.
- Diabetes and gout can worsen, and lupus can flare or appear.
Remember them
A way to remember them
GLUC
- G
- Glucose up
- L
- Lipids up
- U
- Uric acid up
- C
- Calcium up
Think 'hyper-GLUC': thiazides raise blood glucose, lipids, uric acid and calcium, while potassium, sodium and magnesium fall.
A mnemonic widely used in teaching
Name stems
-thiazide, -tizide means thiazide diuretic
Hydrochlorothiazide and bendroflumethiazide keep the older -thiazide spelling; WHO uses -tizide for newer names. Thiazide-like chlortalidone and indapamide don't carry it.
- Every drug name stem
Don't mix them up
Classes easily confused with these
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Thiazide Diuretic (NCI Thesaurus)
- Hydrochlorothiazide tablets: label (DailyMed)
- Chlorthalidone tablets: label (DailyMed)
- Bendroflumethiazide 2.5 mg tablets: SmPC (HPRA)
- Guideline for the pharmacological treatment of hypertension in adults (WHO)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Blood pressure
Practice thiazide and thiazide-like diuretics with the other classes in this group: what each drug is, how it works, what it treats and what it's known for.
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