What are the uses and dosages of Acetazolamide (carbonic anhydrase inhibitor) in various medical conditions?

Acetazolamide: Uses and Dosages in Various Medical Conditions

Acetazolamide is primarily indicated for altitude sickness prevention (125-250 mg twice daily starting 24 hours before ascent), glaucoma (250 mg to 1 g daily in divided doses), epilepsy (8-30 mg/kg daily in divided doses), and congestive heart failure (250-375 mg once daily on alternate days). 1, 2

Approved Indications and Dosages

Glaucoma

• Open-angle glaucoma: 250 mg to 1 g daily in divided doses
• Acute congestive (closed-angle) glaucoma: 250 mg every 4 hours or initial dose of 500 mg followed by 125-250 mg every 4 hours
• Secondary glaucoma: 250 mg every 4 hours
• Note: Dosages over 1 g daily typically do not produce increased effect 2

Epilepsy

• Dosage: 8-30 mg/kg daily in divided doses (375-1000 mg daily)
• Most effective for petit mal in children, but also effective for other seizure types
• When adding to existing anticonvulsants: Start with 250 mg once daily and increase gradually 2

Congestive Heart Failure

• Starting dose: 250-375 mg (5 mg/kg) once daily in the morning
• Most effective when given on alternate days or two days on/one day off
• Skip medication for a day if patient stops losing edema fluid
• Does not eliminate need for other therapies (digitalis, bed rest, salt restriction) 2

High Altitude Sickness Prevention

• Recommended dose: 125-250 mg twice daily starting 24 hours before ascent
• 250 mg/day has similar efficacy to higher doses with potentially fewer side effects
• Particularly important for women who may have higher risk of acute mountain sickness 1, 3

Off-Label Uses

Idiopathic Intracranial Hypertension

• Reduces cerebrospinal fluid production and intracranial pressure
• Helps avoid invasive procedures in patients with CSF leaks or elevated ICP 4

Chronic Mountain Sickness (Monge's Disease)

• 250 mg daily shown to decrease hematocrit by 7.1%, reduce serum erythropoietin by 67%
• Increases nocturnal arterial O₂ saturation by 5%
• Decreases apnea-hypopnea episodes during sleep by 74% 5

Respiratory Support

• May assist in ventilator weaning for COPD patients
• Increases nocturnal arterial O₂ saturation in high-altitude residents 4, 5

Contraindications and Precautions

Absolute Contraindications

• Kidney stones
• Aplastic anemia
• Sickle cell disease
• Sulfa allergy
• Severe hepatic or renal disease
• Adrenocortical insufficiency
• Hyperchloremic acidosis 1

Dosing Adjustments

• For creatinine clearance <50 mL/min: Administer no more frequently than every 12 hours 4

Side Effects and Monitoring

Common Side Effects

• Paresthesias
• Vertigo
• Altered taste
• Allergic dermatitis/conjunctivitis 1

Serious Side Effects

• Kidney stones
• Metabolic acidosis
• Blood dyscrasias
• Stevens-Johnson syndrome
• Serum electrolyte imbalances
• Lethargy
• Suppression of appetite 1

Monitoring Requirements

• Serum electrolytes
• Renal function
• Acid-base status
• Clinical response 1

Important Clinical Considerations

Drug Interactions

• Limit caffeine intake due to potential worsening of side effects
• Avoid combining with other diuretics due to increased risk of dehydration and electrolyte imbalances 1

Altitude Sickness Management

• Acetazolamide is preventive, not curative
• Immediate descent remains the primary treatment for severe altitude illness
• Supplemental oxygen should be administered to maintain saturation >90% 1
• Non-pharmacological prevention includes gradual ascent (300-600m/day above 2500m), rest days, adequate hydration 1

Cardiovascular Considerations

• May reduce risk of subendocardial ischemia at high altitude in patients with coronary artery disease
• Well-controlled hypertensive patients may reach high altitudes with adequate therapy 1

Reconstitution and Storage (Parenteral Form)

• Reconstituted solutions retain properties for 3 days under refrigeration (2-8°C) or 12 hours at room temperature (20-25°C)
• Direct intravenous route preferred; intramuscular administration not recommended
• Contains no preservative 2

The evidence strongly supports acetazolamide as an effective medication across multiple conditions, with dosing regimens that vary significantly based on indication. While higher doses may be needed for conditions like epilepsy, lower doses (250 mg daily) appear equally effective for altitude sickness prevention with fewer side effects 3.