When is Diamox (acetazolamide) given to patients?

When to Give Diamox (Acetazolamide)

Diamox (acetazolamide) should be given primarily for acute mountain sickness (AMS) prophylaxis, glaucoma management, and as adjunctive therapy for certain types of epilepsy and idiopathic intracranial hypertension. 1, 2

High Altitude Illness Prevention and Treatment

For AMS prophylaxis, acetazolamide 125 mg twice daily is the recommended dose, started 1-3 days before ascent and continued for the first 2-3 days at altitude. 1, 3 This lower dose (250 mg/day total) is equally effective as higher doses (750 mg/day) but causes fewer side effects, particularly less paresthesia. 3

Specific High Altitude Indications:

• Rapid ascent from low to high altitude (>2500-3000m): Acetazolamide reduces AMS incidence from 45-60% to 14-24% in high-risk scenarios. 4, 3
• Cardiovascular patients ascending to altitude: Consider acetazolamide for AMS prevention, as it may reduce subendocardial ischemia risk, though data in CAD patients are limited. 1
• Periodic breathing at altitude in heart failure patients: Acetazolamide may suppress this, though evidence remains unclear. 1

Dosing for Altitude:

• Standard prophylaxis: 125 mg twice daily (total 250 mg/day). 3
• Ultra-low dose option: 62.5 mg twice daily may be noninferior for prevention, though studied in limited populations. 5
• Higher doses (375 mg twice daily) offer no additional benefit and increase side effects. 3

Common pitfall: Avoid prescribing acetazolamide doses exceeding 250 mg/day for AMS prophylaxis, as this increases paresthesia without improving efficacy. 3

Glaucoma Management

For chronic open-angle glaucoma, acetazolamide 250 mg to 1 g per 24 hours in divided doses is used as adjunctive therapy. 2 Doses exceeding 1 g/24 hours typically provide no additional benefit. 2

Specific Glaucoma Scenarios:

• Acute angle-closure glaucoma: 250 mg every 4 hours, or 500 mg initial dose followed by 125-250 mg every 4 hours. 2
• Preoperative acute glaucoma: IV administration may be used for rapid IOP reduction. 2
• Secondary glaucoma: 250 mg every 4 hours, adjustable based on response. 2

Acetazolamide works synergistically with miotics or mydriatics in glaucoma management. 2

Idiopathic Intracranial Hypertension (IIH)

For IIH with papilledema threatening vision, acetazolamide is first-line medical therapy, starting at 250-500 mg twice daily and titrating up to a maximum of 4 g/day. 1 However, only 44% of patients tolerate 4 g/day, with most tolerating 1 g/day. 1

IIH Treatment Algorithm:

• Start: 250-500 mg twice daily. 1
• Titrate: Increase gradually based on visual field testing and papilledema response. 1
• Maximum: 4 g/day, though 48% discontinue at mean doses of 1.5 g due to side effects. 1

Critical caveat: Acetazolamide has NOT been shown effective for headache treatment alone in IIH—it should only be used when papilledema threatens vision. 1 Do not prescribe acetazolamide solely for IIH-related headaches. 1

Acetazolamide should NOT be used to reduce elevated intracranial pressure in cryptococcal meningitis, as it causes excess acidosis, hypokalemia, and adverse effects. 1

Epilepsy (Adjunctive Therapy)

For epilepsy, acetazolamide 8-30 mg/kg/day in divided doses is used as adjunctive therapy, with optimal range 375-1000 mg daily. 2 Best results are seen in petit mal seizures in children, though benefit extends to grand mal and mixed patterns. 2

Epilepsy Dosing:

• Starting dose: 250 mg once daily added to existing anticonvulsants. 2
• Titration: Increase to 375-1000 mg/day based on response. 2
• Doses >1 g/day offer no additional benefit. 2

Transition from other anticonvulsants to acetazolamide must be gradual. 2

Congestive Heart Failure (Diuresis)

For CHF diuresis, acetazolamide 250-375 mg once daily in the morning (5 mg/kg) is used, given on alternate days or for 2 days alternating with rest. 2

Key principle: If edema fluid loss stops, do not increase the dose—instead, skip medication for a day to allow kidney recovery. 2 Failures often result from overdosage or excessive frequency. 2

Acetazolamide does not replace digitalis, bed rest, or salt restriction in CHF management. 2

Drug-Induced Edema

For drug-induced edema, acetazolamide 250-375 mg once daily for 1-2 days, alternating with a day of rest, is recommended. 2

Administration Considerations

Route of Administration:

• Preferred route: Direct intravenous (IV) administration. 2
• Not recommended: Intramuscular (IM) injection. 2
• Reconstitution: Each 500 mg vial requires ≥5 mL sterile water; stable 3 days refrigerated or 12 hours at room temperature. 2

Concomitant Diuretic Use:

When combining acetazolamide with other diuretics (especially in cardiovascular patients at altitude), carefully evaluate for increased dehydration and electrolyte imbalance risk. 1 This combination requires close monitoring. 1

Common Side Effects to Warn Patients About:

• Paresthesia (dose-dependent, more common at higher doses). 1, 3
• Dysgeusia (metallic taste). 1
• Increased urination. 2
• Gastrointestinal upset (diarrhea, nausea, vomiting). 1
• Fatigue and tinnitus. 1
• Rare: renal stones, depression. 1

Acetazolamide reduces the efficacy of oral contraceptives—counsel women accordingly. 1