Acetazolamide: Uses and Dosages
Acetazolamide is a carbonic anhydrase inhibitor with multiple therapeutic applications including glaucoma (250 mg-1 g daily), epilepsy (8-30 mg/kg daily), altitude sickness prevention (125-250 mg twice daily), idiopathic intracranial hypertension, and as a diuretic for heart failure (250-375 mg once daily). 1, 2
Primary Indications and Dosing
Glaucoma
- Dosage: 250 mg to 1 g per 24 hours, usually in divided doses for amounts over 250 mg 2
- For acute congestive (closed-angle) glaucoma: 250 mg every four hours, or initial dose of 500 mg followed by 125-250 mg every four hours 2
- Intravenous therapy may be used for rapid relief of ocular tension in acute cases 2
- Works synergistically with miotics or mydriatics 2
Epilepsy
- Dosage: 8-30 mg/kg daily in divided doses 2
- Optimal range: 375-1000 mg daily 2
- When adding to existing anticonvulsants, start with 250 mg once daily and increase gradually 2
- Most effective for petit mal epilepsy in children, but also useful for other seizure types 2, 3
Altitude Sickness Prevention
- Dosage: 125-250 mg twice daily, starting 24 hours before ascent 1
- Reduces risk of acute mountain sickness by 48% compared to placebo 4
- 250 mg/day has similar efficacy to higher doses with potentially fewer side effects 4, 5
Heart Failure/Edema
- Dosage: 250-375 mg once daily in the morning (5 mg/kg) 2
- Best results when given on alternate days or for two days alternating with a day of rest 2
- Does not eliminate need for other therapy such as digitalis, bed rest, and salt restriction 2
Idiopathic Intracranial Hypertension
- Used to reduce cerebrospinal fluid production and intracranial pressure 1, 6
- Helps avoid invasive procedures in patients with CSF leaks or elevated ICP 6
Administration and Pharmacokinetics
- Primarily administered orally; intravenous route preferred when available; intramuscular administration not recommended 2
- Plasma half-life: 4-8 hours, though pharmacologic effects last longer 6
- Highly protein-bound and primarily eliminated by kidneys 6
- For patients with creatinine clearance <50 mL/min, administration should not be more frequent than every 12 hours 6
Contraindications and Precautions
- Contraindicated in patients with:
- Sulfa allergy
- Severe hepatic disease
- Severe renal disease
- Adrenocortical insufficiency
- Hyperchloremic acidosis 1
Monitoring and Side Effects
- Monitor serum electrolytes, renal function, acid-base status, and clinical response 1
- Common side effects:
- Paresthesias
- Vertigo
- Altered taste
- Increased urination
- Dizziness
- Metabolic acidosis 1
- More serious adverse effects:
- Kidney stones
- Lethargy
- Appetite suppression
- Rare blood dyscrasias 3
- Avoid combining with other diuretics due to increased risk of dehydration and electrolyte imbalances 1
- Limit caffeine intake to avoid worsening side effects and impact on treatment efficacy 1
Special Considerations
- Partial tolerance may develop to antiepileptic activity 3
- For altitude sickness, should be combined with proper acclimatization strategies:
- Gradual ascent (300-600m/day above 2500m)
- Rest days
- Adequate hydration
- Avoiding overexertion 1
- Women may have higher risk of acute mountain sickness; pre-acclimatization and slow ascent particularly important 1
Acetazolamide remains a valuable medication across multiple therapeutic areas, with dosing regimens that should be tailored to the specific indication and patient characteristics.