Acetazolamide: Uses and Dosages
Acetazolamide is a carbonic anhydrase inhibitor with established uses for glaucoma, epilepsy, altitude sickness, edema, and idiopathic intracranial hypertension, with dosages ranging from 125-1000 mg daily depending on the indication.
Primary FDA-Approved Indications and Dosages
Glaucoma
- Dosage: 250 mg to 1 g daily, usually in divided doses for amounts over 250 mg 1
- Administration: Oral or intravenous (for acute cases)
- Notes:
- For chronic open-angle glaucoma: 250 mg to 1 g daily
- For acute congestive (closed-angle) glaucoma: 250 mg every 4 hours or 500 mg initially followed by 125-250 mg every 4 hours
- Continuous physician supervision recommended
- May be used with miotics or mydriatics for complementary effect
Epilepsy
- Dosage: 8-30 mg/kg daily in divided doses 1
- Optimal range: 375-1000 mg daily
- Administration: Oral
- Notes:
- Best results seen in petit mal epilepsy in children
- When used with other anticonvulsants, start at 250 mg once daily
- Transition from other medications should be gradual
Congestive Heart Failure (Edema)
- Dosage: 250-375 mg (5 mg/kg) once daily in the morning 1
- Administration: Oral
- Notes:
- Best results when given on alternate days or two days on/one day off
- Does not eliminate need for other therapy (digitalis, bed rest, salt restriction)
- For drug-induced edema: 250-375 mg once daily for 1-2 days, alternating with rest days
Off-Label Uses and Dosages
Altitude Sickness Prevention
- Dosage: 125-250 mg twice daily 2, 3, 4
- Administration: Start 24 hours before ascent
- Efficacy: 48% relative risk reduction compared to placebo 3
- Notes:
Obstructive Sleep Apnea (OSA)
- Dosage: 36-1000 mg daily 5
- Administration: Oral
- Notes:
- European Respiratory Society conditionally recommends use only in research context
- Can reduce sleep apnea intensity (AHI) by up to 45%
- Improves oxygen desaturation index and oxygenation
- No documented effect on excessive daytime sleepiness
Idiopathic Intracranial Hypertension
- Dosage: 250-4000 mg daily divided every 6-12 hours 6
- Administration: Oral
- Notes:
- Decreases production of cerebrospinal fluid
- Reduces intracranial pressure
- May help avoid invasive procedures
Central Serous Chorioretinopathy
- Dosage: 100 mg daily 5
- Administration: Oral
- Notes: Limited evidence for efficacy
Special Populations and Considerations
Renal Impairment
- For creatinine clearance <50 mL/min: Do not administer more frequently than every 12 hours 6
Contraindications
- Sulfa allergy (acetazolamide is a sulfonamide derivative)
- Severe hepatic disease
- Severe renal disease
- Adrenocortical insufficiency
- Hyperchloremic acidosis
Common Adverse Effects
- Paresthesias
- Altered taste of carbonated beverages
- Increased urination
- Metabolic acidosis
- Lethargy
- Appetite suppression
- Vertigo
- Kidney stones 7
Important Precautions
- Avoid combining with other diuretics due to increased risk of dehydration and electrolyte imbalances 5, 2
- Monitor for electrolyte disturbances, particularly hypokalemia
- For high altitude use, do not rely solely on acetazolamide to prevent severe altitude illness; proper acclimatization remains essential 2
- When used for edema management in nephrotic syndrome, may be combined with loop diuretics for synergistic effect 5
Monitoring Parameters
- Serum electrolytes
- Renal function
- Acid-base status
- Clinical response (based on indication)
Acetazolamide's versatility as a medication stems from its mechanism of inhibiting carbonic anhydrase, which affects multiple physiological processes including fluid balance, pH regulation, and cerebrospinal fluid production.