Acetazolamide

Brand Names: Diamox

Drug Class: Carbonic anhydrase inhibitor

Overview

Acetazolamide is a carbonic anhydrase inhibitor used primarily as an adjunctive therapy for glaucoma, edema, epilepsy, and prevention of acute mountain sickness. It reduces intraocular pressure, promotes diuresis, and has anticonvulsant properties through inhibition of carbonic anhydrase enzymes.

Mechanism of Action

Inhibits carbonic anhydrase, an enzyme that catalyzes the reversible hydration of carbon dioxide. This inhibition reduces bicarbonate formation, leading to decreased aqueous humor production (lowering intraocular pressure), increased renal excretion of bicarbonate (diuretic effect), and mild metabolic acidosis that may contribute to anticonvulsant activity.

Indications

  • Adjunctive treatment of chronic simple (open-angle) glaucoma, secondary glaucoma, and preoperative management of acute angle-closure glaucoma
  • Adjunctive treatment of edema due to congestive heart failure and drug-induced edema
  • Adjunctive treatment of centrencephalic epilepsies (petit mal, unlocalized seizures)
  • Prevention or amelioration of symptoms associated with acute mountain sickness

Common Doses

  • 125 mg
  • 250 mg
  • 500 mg

Dosage

Dosage varies by indication: 250-1000 mg daily in divided doses for glaucoma and epilepsy; 250-375 mg once daily or on alternate days for edema; 500-1000 mg daily starting 24-48 hours before ascent for acute mountain sickness prevention. Maximum recommended dose is 1 g daily. Epilepsy is weight-based: 8–30 mg/kg/day Doses above 1 g/day generally show no added benefit (not a strict universal maximum) Edema includes structured “rest day” guidance

Contraindications

  • Hypersensitivity to acetazolamide or sulfonamide derivatives
  • Depressed serum sodium/potassium levels
  • Marked kidney or liver disease/dysfunction
  • Suprarenal gland failure
  • Hyperchloremic acidosis
  • Cirrhosis (risk of hepatic encephalopathy)
  • Chronic noncongestive angle-closure glaucoma (long-term use)

Side Effects

  • Common: paresthesia, fatigue, nausea, diarrhea, taste alteration, drowsiness, dizziness
  • Serious: metabolic acidosis, electrolyte imbalances (hypokalemia, hyponatremia), blood dyscrasias (aplastic anemia, agranulocytosis), severe skin reactions (Stevens-Johnson syndrome), hepatic toxicity, renal stones, transient myopia

Interactions

  • High-dose aspirin: increased risk of metabolic acidosis and CNS toxicity
  • May interfere with laboratory tests for urinary protein, serum uric acid, and theophylline assays
  • Concomitant use with other carbonic anhydrase inhibitors may increase adverse effects

Counseling Points

  • Take with food if gastrointestinal upset occurs
  • Report signs of infection, unusual bleeding/bruising, severe skin reactions, or vision changes immediately
  • Maintain adequate hydration to reduce kidney stone risk
  • Avoid rapid position changes if experiencing dizziness
  • Use sun protection due to photosensitivity risk
  • Do not take high-dose aspirin without medical supervision