II. Mechanism

  1. Diuretic in the Carbonic Anhydrase Inhibitor Class
  2. Decreases secretion of Aqueous Humor (Glaucoma)
  3. Decreases Hydrogen Ion at renal proximal tubule
    1. Prevents renal bicarbonate reuptake resulting in urine alkalization (and blood acidification)
    2. Increased renal excretion of Sodium, Potassium, bicarbonate and water
    3. Results in hypokalemic Metabolic Acidosis and Respiratory Alkalosis (mechanism in High Altitude Illness)
      1. Lower resting PaCO2
      2. Higher resting Minute Ventilation
      3. Increased PaO2

III. Indications

  1. High Altitude Sickness treatment and prevention
  2. Pseudotumor Cerebri
  3. Glaucoma
    1. Intraocular Carbonic Anhydrase Inhibitor
      1. Open Angle Glaucoma
    2. Systemic Acetazolamide (IV or oral) Indications
      1. Acute angle closure Glaucoma before surgery
      2. Acute exacerbation of chronic Open Angle Glaucoma
  4. Other indications
    1. Periodic Paralysis
    2. Marfan Syndrome related dural ectasia
    3. Stable Hypercapnic Respiratory Failure (respiratory stimulant)
    4. Epilepsy
      1. FDA approved for Seizures since 1956
      2. Has been used for Catamenial Epilepsy, Myoclonic, Absence and Generalized Seizures
      3. Reiss (1996) Ann Pharmacother 30(5):514-9 [PubMed]

V. Dosing

  1. High Altitude Sickness
    1. Prevention
      1. Adults: 125 mg orally every 12 hours (FDA approved)
        1. Up to 250 mg twice daily may be used (but 125 mg is typically sufficient)
        2. Doses of 1000 mg/day (with added Dexamethasone) have been used for rapid ascent (e.g. rescue)
      2. Children: 2.5 mg/kg up to 125 mg every 12 hours (off-label)
      3. Start 24 hours before ascent
      4. Continue for 72 hours or until acclimitization to highest sleeping altitude
    2. Insomnia at altitude: 125 mg orally at bedtime
    3. Treatment: Adults
      1. Start: 250 mg orally twice daily
      2. Range: 500 to 1000 mg/day divided every 8 to 12 hours (every 12 to 24 hours if extended release)
      3. Often used in combination with Dexamethasone
  2. Pseudotumor Cerebri
    1. Dose range: 125-250 mg orally daily to three times daily
  3. Open Angle Glaucoma acute exacerbation or Acute Narrow Angle Glaucoma prior to surgery
    1. Dose: 250 mg orally or IV every 4-6 hours (maximum 1 gram/day)

VI. Adverse Effects: Common

  1. Hypokalemia
  2. Hyponatremia
  3. Metabolic Acidosis
  4. Peripheral Paresthesias (common)
  5. Polyuria
  6. Taste Dysfunction (Dysgeusia) with bitter or Metallic Taste
  7. Headache
  8. Nausea or Vomiting
  9. Abdominal Cramping
  10. Black Stool
  11. Diarrhea
  12. Fatigue
  13. Drowsiness
  14. Depressed Mood
  15. Decreased Libido
  16. Ureteral Stones

VII. Adverse Effects: Uncommon Serious

VIII. Drug Interactions

IX. Safety

  1. Pregnancy Category C

X. References

  1. Olson (2020) Clinical Pharmacology, Medmaster, Miami, p. 62-3
  2. Hamilton (2010) Tarason Pocket Pharmacopeia, p. 224
  3. Lovecchio (2017) Crit Dec Emerg Med 31(8): 28
  4. Lovecchio (2022) Crit Dec Emerg Med 36(3): 28

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Related Studies

Cost: Medications

acetazolamide (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
ACETAZOLAMIDE 125 MG TABLET Generic $1.55 each
ACETAZOLAMIDE 250 MG TABLET Generic $1.82 each
ACETAZOLAMIDE ER 500 MG CAP Generic $1.69 each

Ontology: Acetazolamide (C0000981)

Definition (NCI) A sulfonamide derivative with diuretic, antiglaucoma, and anticonvulsant properties. Acetazolamide is a non-competitive inhibitor of carbonic anhydrase, an enzyme found in cells in the proximal tube of the kidney, the eye, and glial cells. Inhibition of this enzyme in the kidney prevents excretion of hydrogen, leading to increased bicarbonate and cation excretion and increased urinary volume, which results in an alkaline diuresis. Acetazolamide reduces the concentration of bicarbonate, resulting in a decreased synthesis of aqueous humor in the eye, thereby lowering intraocular pressure. Although its mechanism of action is unknown, acetazolamide has anti-convulsant properties resulting from indirect effects secondary to metabolic acidosis or direct effects on neuronal transmission. Acetazolamide also produces respiratory stimulant effects in response to changes to both carbon dioxide and oxygen tension levels within the lungs.
Definition (MSH) One of the CARBONIC ANHYDRASE INHIBITORS that is sometimes effective against absence seizures. It is sometimes useful also as an adjunct in the treatment of tonic-clonic, myoclonic, and atonic seizures, particularly in women whose seizures occur or are exacerbated at specific times in the menstrual cycle. However, its usefulness is transient often because of rapid development of tolerance. Its antiepileptic effect may be due to its inhibitory effect on brain carbonic anhydrase, which leads to an increased transneuronal chloride gradient, increased chloride current, and increased inhibition. (From Smith and Reynard, Textbook of Pharmacology, 1991, p337)
Definition (CSP) carbonic anhydrase inhibitor that is sometimes effective against seizures.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D000086
SnomedCT 330592008, 391705005, 322853009, 372709008, 33664007
LNC LP16018-1, MTHU005569
English Acetamide, N-(5-(aminosulfonyl)-1,3,4-thiadiazol-2-yl)-, Acetazolamide [epilepsy], Acetazolamide [glaucoma], N-(5-(Aminosulfonyl)-1,3,4-thiadiazol-2-yl)acetamide, acetazolamide, acetazolamide (medication), ACETAZOLAMIDE, Acetazolamide [Chemical/Ingredient], acetazolamides, acetaZOLAMIDE, Acetazolamide [glaucoma] (product), Acetazolamide - chemical, Acetazolamide - chemical (substance), Acetazolamide [epilepsy] (product), N-[5-(Aminosulfonyl)-1,3,4-thiadiazol-2-yl]acetamide, Acetazolamide (product), Acetazolamide (substance), Acetazolamide [epilepsy] (substance), Acetazolamide [glaucoma] (substance), Acetazolamide, AcetaZOLAMIDE
Swedish Acetazolamid
Czech acetazolamid
Finnish Asetatsoliamidi
Polish Diamoks, Acetazolamid
Japanese アセタゾールアミド, アセタゾラミド
Spanish acetazolamida - sustancia química, acetazolamida - sustancia química (sustancia), acetazolamida (antiglaucomatoso) (producto), acetazolamida (antiglaucomatoso), acetazolamida (antiepiléptico), acetazolamida (antiepiléptico) (producto), acetazolamida (glaucoma) (producto), acetazolamida (glaucoma), acetazolamida (producto), acetazolamida (sustancia), acetazolamida [epilepsia] (producto), acetazolamida [epilepsia], acetazolamida, Acetazolamida
French Acétazolamide
German Acetazolamid, Azetazolamid
Italian Acetazolamide
Portuguese Acetazolamida

Ontology: Diamox (C0591362)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D000086
English diamox, Cyanamid Brand of Acetazolamide Preparation, Lederle Brand of Acetazolamide Preparation, Storz Brand of Acetazolamide Preparation, Whelehan Brand of Acetazolamide Preparation, Wyeth Brand of Acetazolamide Preparation, Diamox, Théraplix Brand of Acetazolamide Preparation