Acetazolamide

General

• Type: Carbonic anhydrase inhibitor
• Dosage Forms: PO/IV
• Common Trade Names: Diamox

Adult Dosing

Glaucoma

• Closed-angle Glaucoma:
  • 500mg PO/IV, followed by 125-250mg PO q4h
  • 500mg PO q12h (sustained release)
• Open-angle Glucoma:
  • 250mg-1g PO/IV QD
  • 500mg PO q12h (sustained release)

Acute altitude sickness

Treatment

• 500-1000mg extended release PO QD
• Continue treatment for 48 hours or longer if necessary

Prophylaxis

• 125mg PO BID
• Start 24hr before ascent and continue for the first 48hrs at peak altitude

CHF-associated Edema

• 250-375mg PO qAM
• 5mg/kg

Drug-induced Edema

• 250-375mg PO qAM

Epilepsy

• 8-30mg/kg/day PO QD
• Do not exceed 30mg/kg/day or 1g/day

Off-label use

• Familial periodic paralysis; Hydrocephalus, normal-pressure; Idiopathic intracranial hypertension; Metabolic alkalosis; Prevention of cystine renal calculi (adjunctive therapy); Respiratory stimulant in stable hypercapnic COPD

Pediatric Dosing

Epilepsy

• <12 years: safety and efficacy not established
• >12 years: 8-30mg/kg/day PO QD

Acute altitude sickness

Treatment

• <12 years: safety and efficacy not established
• >12 years: 500-1000mg PO QD

Prophylaxis

• 2.5mg/kg/dose (maximum 125mg/dose) PO every 12 hours
• Start 24hr before ascent and continue for the first 48hrs at peak altitude

Special Populations

• Pregnancy Rating: C
• Lactation risk: Safe
• Renal Dosing
  • Adult: CrCl 10-50: give q12h; CrCl<10: avoid use; HD/PD: not defined
  • Pediatric: CrCl 10-50: give q12h; CrCl<10: avoid use, HD/PD: not defined
• Hepatic Dosing
  • Adult: contraindicated in significant impairment/cirrhosis
  • Pediatric: contraindicated in significant impairment/cirrhosis
  • Geriatric: Refer to adult dosing. Oral: Initial doses should begin at the low end of the dosage range.

Contraindications

• Allergy to class/drug
• hypokalemia
• hyponatremia
• acidosis, hyperchloremic
• acidosis, metabolic
• adrenal insufficiency
• cirrhosis
• hepatic disease, severe
• renal disease, severe
• glaucoma, angle-closure (long-term use)
• caution if hypersensitivity to sulfonamides
• caution if ASA treatment, high-dose
• caution if hepatic impairment
• caution if pulmonary impairment
• caution if diabetes mellitus
• caution if gout
• caution if elderly patients

Adverse Reactions

Serious

• metabolic acidosis
• electrolyte imbalance
• anaphylaxis
• erythema multiforme
• Stevens-Johnson syndrome
• toxic epidermal necrolysis
• hepatic necrosis
• hepatic impairment
• agranulocytosis
• anemia, hemolytic
• myelosuppression
• leukopenia
• pancytopenia
• blood dyscrasias
• thrombocytopenic purpura
• seizures
• paralysis, flaccid
• crystalluria
• nephrolithiasis

Common

• fatigue
• malaise
• taste change
• anorexia
• nausea/vomiting
• parethesia
• diarrhea
• polyuria
• electrolyte disorders
• tinnitus
• hearing changes
• myopia
• drowsiness
• confusion
• uticaria
• rash
• photosensitivity
• glucosuria
• hematuria
• melena

Pharmacology

• Half-life: 10-15h
• Metabolism: CYP450
• Excretion: urine (100% unchanged)
• Mechanism of Action: inhibits carbonic anhydrase

Indications by Condition

The following table is automatically generated from disease/condition pages across WikEM.

Indication	Dose	Context	Route	Population
Acute mountain sickness	125-250mg BID	Mild AMS; speeds acclimatization via bicarb diuresis	PO	Adult
Acute mountain sickness	250mg BID	Moderate-severe AMS	PO	Adult
High altitude cerebral edema	250mg BID	Adjunctive; better as prophylaxis	PO	Adult
Idiopathic intracranial hypertension	250mg QID or 500mg BID (titrate up to 500-1000mg QID)	Decrease CSF production	PO	Adult
Orbital compartment syndrome	250-500mg IV	Reduce intraocular pressure	IV	Adult
Retrobulbar hemorrhage	250-500mg IV	Reduce intraocular pressure	IV	Adult
Volume overload	500mg IV daily on top of loop diuretic	ADVOR trial, added to loop diuretic for decongestion	IV	Adult

References

• Acetazolamide injection [prescribing information]. Big Flats, NY: X-Gen Pharmaceuticals, Inc; October 2015.