Acetazolamide (Diamox) Dosing Frequency
Acetazolamide is typically dosed twice daily (every 12 hours) for most indications, with specific dosing ranging from 125 mg twice daily to 500 mg twice daily depending on the condition being treated.
Dosing by Indication
Glaucoma
- Standard dosing: 250 mg to 1 g total daily dose, usually in divided doses for amounts over 250 mg 1
- Frequency: Doses exceeding 250 mg should be split throughout the day
- Acute glaucoma: 250 mg every 4 hours, or initial 500 mg followed by 125-250 mg every 4 hours 1
Acute Mountain Sickness (AMS) Prevention
- Recommended dose: 125 mg twice daily (every 12 hours) 2, 3
- Timing: Start 24-48 hours before ascent and continue while at altitude 1, 2
- Alternative: 500 mg once daily extended-release formulation 4
- Higher altitude/rapid ascent: 500-1000 mg daily in divided doses for rapid ascent situations 1
Important caveat: Research shows 62.5 mg twice daily is inferior to 125 mg twice daily and should NOT be used 5. Day-of-ascent dosing (starting morning of ascent rather than night before) showed slightly higher AMS rates and just exceeded the noninferiority margin, though severe AMS was actually lower 6.
Central Sleep Apnea
- Dosing range: 250-1000 mg daily in divided doses 7
- Duration: Studies evaluated 3-6 nights of treatment 7
- Monitoring: If used as replacement/additional diuretic in heart failure patients, reassess electrolytes after 2-4 weeks 7
Idiopathic Intracranial Hypertension (IIH)
- Starting dose: 250-500 mg twice daily 8
- Titration: Gradually increase daily dose as tolerated
- Maximum studied: 4 g daily (though only 44% of patients tolerated this dose; majority tolerated 1 g/day) 8
- Common maintenance: Most clinicians titrate upward from starting dose 8
Heart Failure/Edema
- Dosing: 250-375 mg once daily in the morning 1
- Key principle: Give on alternate days or for 2 days alternating with a day of rest for best diuretic results 1
- Rationale: Allows kidney recovery from carbonic anhydrase inhibition 1
Epilepsy
- Total daily dose: 8-30 mg/kg in divided doses 1
- Optimal range: 375-1000 mg daily 1
- Starting with other anticonvulsants: 250 mg once daily, then increase as needed 1
Critical Dosing Principles
The frequency depends on whether the therapeutic effect requires continuous carbonic anhydrase inhibition:
Glaucoma and epilepsy: Require consistent dosing (twice daily or more frequent) because they depend on sustained enzyme inhibition in the eye/CNS, not kidney recovery 1
Diuresis (heart failure, edema): Requires intermittent dosing (alternate days or with rest days) to allow kidney recovery from carbonic anhydrase inhibition 1
Common Side Effects to Monitor
- Paresthesias (hands/feet)
- Altered taste (dysgeusia)
- Increased urination
- Fatigue, nausea
- Hypokalemia (monitor electrolytes, especially in heart failure patients) 8, 7
- Rarely: kidney stones, depression 8
Practical Algorithm
- Identify the indication (determines base frequency)
- For AMS prevention: Use 125 mg twice daily starting 24-48 hours pre-ascent
- For glaucoma/epilepsy: Use divided doses throughout the day (no rest days)
- For diuresis: Use once daily with planned rest days to allow kidney recovery
- For IIH: Start 250-500 mg twice daily, titrate based on symptoms and ICP
- Monitor electrolytes if using for diuresis or in heart failure patients