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[1]
  • 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

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[2]
  • 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

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

Comments

See Also

References

  1. Luks AM, McIntosh SE, Grissom CK, et al. Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness: 2014 Update. Wilderness & Environmental Medicine. 2014(25): S4–S14)
  2. Luks AM, McIntosh SE, Grissom CK, et al. Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Acute Altitude Illness: 2014 Update. Wilderness & Environmental Medicine. 2014(25): S4–S14)