Pharm 101: Hydrochlorothiazide

Class

Thiazide diuretic


Pharmacodynamics
  • 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)

Pharmacokinetics
  • 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

Precautions/contraindications
  • Drug interactions:
    • Increased plasma Lithium level
    • NSAIDs can reduce effects

Further reading

References

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU Emergency Medicine Trainee with interests in medical education, ECG interpretation, and the use of point-of-care ultrasound in the undifferentiated patient. Co-author of the LITFL ECG Library | Twitter

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