Overview
Hydrochlorothiazide is a thiazide diuretic used primarily to treat hypertension and edema. It works by inhibiting sodium reabsorption in the distal convoluted tubule of the nephron, promoting water and electrolyte excretion.
Mechanism of Action
Inhibits sodium-chloride symporter in the distal convoluted tubule of the nephron, increasing excretion of sodium, chloride, and water. Also causes mild vasodilation.
Indications
- Hypertension
- Edema associated with heart failure, cirrhosis, or renal dysfunction
- Diabetes insipidus
- Calcium nephrolithiasis
Dosage
Hypertension: 12.5-50 mg once daily. Edema: 25-100 mg daily in single or divided doses. Maximum dose: 100 mg/day.
Contraindications
- Anuria
- Hypersensitivity to hydrochlorothiazide or sulfonamide-derived drugs
- Severe renal impairment
- Refractory hypokalemia
- Hypercalcemia
Side Effects
- Hypokalemia
- Hyponatremia
- Hypomagnesemia
- Hypercalcemia
- Hyperglycemia
- Hyperuricemia
- Dizziness
- Headache
- Photosensitivity
- Gastrointestinal disturbances
Interactions
- Lithium (increased lithium toxicity)
- NSAIDs (reduced diuretic effect)
- Digoxin (increased risk of digoxin toxicity with hypokalemia)
- Corticosteroids (enhanced hypokalemia)
- Cholestyramine/colestipol (reduced absorption)