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

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

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

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

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

References

Authors

Tasha Fernando, Bobak Zonnoor, Ross Donaldson, Daniel Ostermayer, Neil Young