Pharm 101: Hydrochlorothiazide


Thiazide diuretic

  • Inhibit Na/Cl co-transporter in distal convoluted tubule
  • Reduces NaCl reabsorption form luminal side of epithelial cells
  • Leads to increased NaCl excretion and diuresis
  • Enhanced Ca reabsorption (passive)
  • Duration of action 8-12 hours
  • Secreted by organic acid secretory system in proximal tubule
    • Compete with uric acid secretion by same system
Clinical uses
  • Hypertension
  • Heart failure
  • Nephrolithiasis due to idiopathic hypercalciuria
  • Nephrogenic diabetes insipidus
Adverse effects
  • Dehydration/hypovolaemia
  • Hypokalaemic metabolic alkalosis (similiar to loop diuretics)
  • Hyperglycaemia
  • Unmask hypercalcaemia due to other causes
  • Hyperlipidaemia
  • Hyponatraemia
  • Hyperuricaemia
  • Drug interactions:
    • Increased plasma Lithium level
    • NSAIDs can reduce effects
Further reading

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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