Last Updated on August 19, 2026
Classifications:
(i) Thiazide e.g.
hydrochlorothiazide
Most commonly used thiazide in Malaysia
(ii) Thiazide-like diuretics e.g. chlorthalidone (CTD), indapamide
Mechanisms of Action
- Blocks Na+-Cl− co-transporter at the beginning of distal convoluted tubule → inhibits odium re absorption
- Natriuretics would alter long term sodium balance → reduced peripheral vascular resistance & sustained BP reduction
- As more sodium reaching collecting duct, hypokalaemia occurs
Indications
- Hypertension
Adverse effects
- Electrolyte imbalance
-
Hyponatremia
×
a typical complication of thiazide diuretics
-
Hypokalaemia
×
Hypokalaemia may cause digoxin toxicity
-
Hypercalcaemia
×
• Reduced calcium excretion → hypocalciuria would reduce risk of renal stones
-
Hyponatremia
- Urinary frequency
-
Dehydration
×Dehydration
Dehydration
-
Postural hypotension
×Postural hypotension
Postural hypotension: https://www.myhouseman.my/hypotension/
-
Gout
×
Thiazide → reduced excretion of uric acid → hyperuricaemia → gout
-
Erectile dysfunction
×
Reversible
- Impaired glucose tolerance
Rare adverse effects
- Thrombocytopenia
- Photosensitivity rashes
- Pancreatitis
Dosage
Hypertension
- Single / combine with other anti-HTN
Diuretics | Starting dose | Recommended maximum daily dose | Remark |
Hydrochlorothiazide | 12.5 mg OD | 25 mg OD | >25 mg OD more likely to cause electrolyte (esp
hyponatraemia
Visit post: https://www.myhouseman.my/hyponatraemia/ |
Amiloride/hydrochlorothiazide 5 mg/50 mg | 1 Tab OD | 1 Tab OD | |
Indapamide SR | 1.5 mg OD | 1.5 mg OD |