Last Updated on October 16, 2022
Classifications:
(i) Thiazide e.g. hydrochlorothiazide
(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
- Hypokalaemia
- Hypercalcaemia
- Urinary frequency
- Dehydration
- Postural hypotension
- Gout
- Erectile dysfunction
- 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) & metabolic adverse effect |
Amiloride/hydrochlorothiazide 5 mg/50 mg | 1 Tab OD | 1 Tab OD | |
Indapamide SR | 1.5 mg OD | 1.5 mg OD |