What are the uses and dosages of Acetisol (acetazolamide)?

Uses and Dosages of Acetazolamide (Acetisol)

Acetazolamide is a carbonic anhydrase inhibitor with multiple clinical applications including glaucoma, epilepsy, edema, altitude sickness, and idiopathic intracranial hypertension, with specific dosing regimens for each indication.

Primary FDA-Approved Indications and Dosages

Glaucoma

• For chronic simple (open-angle) glaucoma: 250 mg to 1 g daily, usually in divided doses for amounts over 250 mg 1
• For secondary glaucoma and preoperative treatment of acute congestive (closed-angle) glaucoma: 250 mg every four hours, though some cases respond to 250 mg twice daily 1
• Sustained-release capsules (500 mg) once daily provide substantial pressure-lowering effect lasting at least 23 hours, though magnitude is less than with higher dosages 2
• One 500 mg sustained-release capsule twice daily appears as effective as 250 mg tablets four times daily 2

Epilepsy

• Suggested total daily dose: 8 to 30 mg/kg in divided doses 1
• Optimum range appears to be 375 to 1000 mg daily 1
• When used in combination with other anticonvulsants, starting dose should be 250 mg once daily 1
• Primarily used as adjunctive therapy, though may be used as monotherapy in some cases 3
• May be beneficial in partial, myoclonic, absence, and primary generalized tonic-clonic seizures uncontrolled by other agents 3

Congestive Heart Failure (Edema)

• Starting dose: 250 to 375 mg (5 mg/kg) once daily in the morning 1
• Best results when given on alternate days or for two days alternating with a day of rest 1
• Can be used in combination with other diuretics for resistant edema in nephrotic syndrome 4

Off-Label Uses and Dosages

Idiopathic Intracranial Hypertension

• Used to reduce cerebrospinal fluid production and intracranial pressure 4
• Dosage range varies widely (250-1000 mg daily) 4
• The IIHTT (Idiopathic Intracranial Hypertension Treatment Trial) used a maximal dose of 4 g daily, with 44% of participants achieving this dose, though most tolerated 1 g/day 4
• A common starting dose is 250-500 mg twice daily, with gradual titration 4
• Not shown to be effective for treatment of headache alone in IIH 4
• Use during pregnancy requires careful risk-benefit assessment due to potential teratogenic effects in animal studies 4

Obstructive Sleep Apnea

• Has been shown to reduce sleep apnea intensity (AHI) by up to 45% in unselected groups 4
• Dose range in trials: 36-1000 mg daily 4
• European Respiratory Society suggests use only in research context due to limited evidence 4
• Improves oxygen desaturation index and oxygenation but has no documented effect on excessive daytime sleepiness 4

High Altitude Illness Prevention

• Commonly used for mountain sickness prophylaxis 4
• At high altitude, acetazolamide improves nocturnal oxygen saturation and reduces blood pressure increases 4
• May reduce the risk of subendocardial ischemia at high altitude in healthy subjects 4

Administration Considerations

• For patients with renal impairment: administration should not be more frequent than every 12 hours if creatinine clearance is less than 50 mL/min 5
• Plasma half-life is 4-8 hours, though pharmacologic effects last longer 5
• Highly protein bound and primarily eliminated by the kidneys 5

Adverse Effects

• Common side effects include paraesthesias (number needed to harm: 2.3), taste disturbances (NNH: 18), polyuria (NNH: 17), and fatigue (NNH: 11) 6
• Risk of paraesthesias and taste disturbances increases with higher doses 6
• Other adverse effects include metabolic acidosis, kidney stones, lethargy, appetite suppression, and rare blood dyscrasias 3
• When used with other diuretics, monitor for hypokalemia, hyponatremia, impaired GFR, and volume depletion 4
• Approximately 30% of patients experience at least one adverse event 7

Special Considerations

• In heart failure patients at high altitude, concomitant administration of acetazolamide with other diuretics may increase risk of dehydration and electrolyte imbalances 4
• For resistant edema in nephrotic syndrome, acetazolamide may be used as part of combination diuretic therapy 4
• May help treat metabolic alkalosis but is considered a weak diuretic 4