Medically reviewed on March 25, 2018.
(a set a ZOLE a mide)
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Capsule Extended Release 12 Hour, Oral:
Diamox Sequels: 500 mg [DSC]
Generic: 500 mg
Solution Reconstituted, Injection [preservative free]:
Generic: 500 mg (1 ea)
Generic: 125 mg, 250 mg
Brand Names: U.S.
- Diamox Sequels [DSC]
- Anticonvulsant, Miscellaneous
- Carbonic Anhydrase Inhibitor
- Diuretic, Carbonic Anhydrase Inhibitor
- Ophthalmic Agent, Antiglaucoma
Reversible inhibition of the enzyme carbonic anhydrase resulting in reduction of hydrogen ion secretion at renal tubule and an increased renal excretion of sodium, potassium, bicarbonate, and water. Decreases production of aqueous humor and inhibits carbonic anhydrase in central nervous system to retard abnormal and excessive discharge from CNS neurons.
Appears to be dose dependent; erratic with daily doses >10 mg/kg
Erythrocytes, kidneys; blood-brain barrier and placenta; distributes into milk (~30% of plasma concentrations)
Urine (70% to 100% [IV, tablet], 47% [extended release capsule] as unchanged drug within 24 hours)
Onset of Action
Capsule (extended release): 2 hours; Tablet (immediate release): 1 to 1.5 hours; IV: 2 to 10 minutes
Peak effect: Capsule (extended release): 8 to 18 hours; IV: 15 minutes; Tablet: 2 to 4 hours
Time to Peak
Plasma: Capsule (extended release): 3 to 6 hours; Tablet: 1 to 4 hours; IV: 15 minutes
Duration of Action
Inhibition of aqueous humor secretion: Capsule (extended release): 18 to 24 hours; IV: 4 to 5 hours; Tablet: 8 to 12 hours
2.4 to 5.8 hours
Use: Labeled Indications
Altitude illness: Prevention or amelioration of symptoms associated with acute mountain sickness (immediate and extended release dosage forms)
Edema: Adjunctive treatment of drug-induced edema or edema due to congestive heart failure (IV and immediate release dosage forms)
Epilepsy: Adjunctive treatment of centrencephalic epilepsies (IV and immediate release dosage forms)
Glaucoma: Adjunctive treatment of glaucoma (chronic simple open-angle, secondary glaucoma, preoperatively in acute angle-closure)
Off Label Uses
Familial periodic paralysis
Limited data from controlled trials and case reports suggest that acetazolamide may have some benefits in the treatment of hypokalemic and hyperkalemic periodic paralysis. Studies have shown that acetazolamide improves muscle strength in patients with hypokalemic periodic paralysis. In patients with hyperkalemic periodic paralysis, acetazolamide may decrease the steady-state potassium exchange rates and increase potassium uptake by other tissues, resulting in protection from hyperkalemic paralysis. Further controlled studies enrolling more patients are needed to determine the role of acetazolamide in the treatment of familial periodic paralysis.
Data from a limited number of patients in a retrospective review suggest that low-dose acetazolamide can reduce periventricular hyperintensities leading to gait improvement in patients with normal pressure hydrocephalus [Alperin 2014]. Additional data may be necessary to further define the role of acetazolamide in this condition.
Idiopathic intracranial hypertension
Data from a multicenter, randomized, double-masked, placebo-controlled study supports the use of acetazolamide (in combination with weight reduction and low sodium diet) in patients with idiopathic intracranial hypertension (III) and mild vision loss. In this study acetazolamide was associated with modest improvement in the primary endpoint of perimetric visual field function as well as secondary endpoints of papilledema grade, cerebrospinal fluid pressure, and vision-related quality of life measured at 6 months [Wall 2014]. Additional data may be necessary to further define the role of acetazolamide in this condition.
Data from a randomized placebo-controlled, double blinded study in critically-ill medical patients [Mazur 1999] and an open label, uncontrolled, unblinded study [Marik 1991] supports the use of acetazolamide in the treatment of metabolic alkalosis. Additional trials may be necessary to further define the role of acetazolamide in this condition.
Prevention of cystine renal calculi (adjunctive therapy)
Data from a limited number of patients in a retrospective review suggest that acetazolamide may have some benefits as adjunctive therapy for urinary alkalinization in the prevention of cystine renal calculi formation in patients who are recalcitrant to potassium citrate therapy. Additional data may be necessary to further define the role of acetazolamide in this condition.
Respiratory stimulant in stable hypercapnic COPD
Data from a randomized, double-blind, crossover study supports the use of acetazolamide as a respiratory stimulant in the treatment of stable hypercapnic COPD [Wagenaar 2003]. Additional trials may be necessary to further define the role of acetazolamide in this condition.
Hypersensitivity to acetazolamide, sulfonamides, or any component of the formulation; marked hepatic disease or insufficiency; decreased sodium and/or potassium levels; adrenocortical insufficiency; cirrhosis; hyperchloremic acidosis; severe renal disease or dysfunction; long-term use in noncongestive angle-closure glaucoma
Note: Although the FDA approved product labeling states this medication is contraindicated with other sulfonamide-containing drug classes, the scientific basis of this statement has been challenged. See “Warnings/Precautions” for more detail.
Note: IM administration is not recommended because of pain secondary to the alkaline pH.
Altitude illness: Oral: Manufacturer's labeling: 500 to 1,000 mg/day in divided doses every 8 to 12 hours (immediate release tablets) or divided every 12 to 24 hours (extended release capsules). These doses are associated with more frequent and/or increased side effects. Alternative dosing has been recommended:
Prevention: 125 mg twice daily; beginning either the day before (preferred) or on the day of ascent; may be discontinued after staying at the same elevation for 2 to 3 days or if descent initiated (Basnyat 2006; Luks 2010). Note: In situations of rapid ascent (such as rescue or military operations), 1,000 mg/day is recommended by the manufacturer. The Wilderness Medical Society recommends consideration of using dexamethasone in addition to acetazolamide in these situations (Luks 2010).
Treatment: 250 mg twice daily. Note: With high altitude cerebral edema, dexamethasone is the primary treatment; however, acetazolamide may be used adjunctively with the same treatment dose (Luks 2010).
Edema: Oral, IV: 250 to 375 mg once daily
Epilepsy: Oral: 8 to 30 mg/kg/day in divided doses. A lower dosing range of 4 to 16 mg/kg/day in 1 to 4 divided doses has also been recommended; maximum dose: 30 mg/kg/day or 1 g/day (Oles 1989; Reiss 1996). Note: Minimal additional benefit with doses >16 mg/kg/day. Extended release capsule is not recommended for treatment of epilepsy.
Familial periodic paralysis (off-label use): Oral: 125 mg 3 times daily (Links 1988) or 250 mg once daily (Venance 2004) or 250 mg every 6 hours (Hoskins 1974). Additional data may be necessary to further define the role of acetazolamide in the treatment of this condition.
Glaucoma: Oral, IV:
Chronic simple (open-angle): 250 mg 1 to 4 times/day or 500 mg extended release capsule twice daily
Secondary or acute (closed-angle): Initial: 250 to 500 mg; maintenance: 125 to 250 mg every 4 hours (250 mg every 12 hours has been effective in short-term treatment of some patients).
Hydrocephalous, normal pressure (off-label use): Oral: Initial: 125 mg/day; may increase dose up to 375 mg/day (Alperin 2014).
Idiopathic intracranial hypertension (off-label use): Oral: Initial: 500 mg twice daily; may increase dose as tolerated at intervals of 250 mg/week, up to 4,000 mg/day (Wall 2014).
Metabolic alkalosis (off-label use): IV: 500 mg as a single dose; reassess need based upon acid-base status (Marik 1991; Mazur 1999)
Prevention of cystine renal calculi (adjunctive therapy) (off-label use): Oral: 500 mg daily at bedtime in combination with potassium citrate and captopril (Sterrett 2008)
Respiratory stimulant in stable hypercapnic COPD (off-label use): Oral: 250 mg twice daily (Wagenaar 2003)
Refer to adult dosing. Oral: Initial doses should begin at the low end of the dosage range.
Note: IM administration is not recommended because of pain secondary to the alkaline pH.
Edema: Limited data available: Infants, Children, and Adolescents: Oral (immediate release), IV: 5 mg/kg/dose every other day in the morning (Pagliaro 2002).
Epilepsy: Oral: Refer to adult dosing.
Altitude illness: Oral:
Prevention: 2.5 mg/kg/dose every 12 hours started either the day before (preferred) or on the day of ascent and may be discontinued after staying at the same elevation for 2-3 days or if descent initiated; maximum dose: 125 mg/dose (Luks 2010). Note: The International Society for Mountain Medicine does not recommend prophylaxis in children except in the rare circumstance of unavoidable rapid ascent or in children with known previous susceptibility to acute mountain sickness (Pollard 2001).
Treatment: 2.5 mg/kg/dose every 8-12 hours; maximum dose: 250 mg/dose. Note: With high altitude cerebral edema, dexamethasone is the primary treatment; however, acetazolamide may be used adjunctively with the same treatment dose (Luks 2010; Pollard 2001).
Dosing: Renal Impairment
Mild to moderate impairment: There are no dosage adjustments provided in the manufacturer's labeling.
Severe impairment: Use is contraindicated.
Hemodialysis: Dialyzable. Avoid use unless dose is reduced and serum concentrations can be monitored; monitor patients closely for CNS toxicity (Schwenk 1995).
Peritoneal dialysis: Supplemental dose is not necessary (Schwenk 1994).
Dosing: Hepatic Impairment
Use is contraindicated in patients with cirrhosis or marked liver disease or dysfunction.
Injection: Reconstitute with at least 5 mL sterile water to provide a solution containing not more than 100 mg/mL.
A 25 mg/mL oral suspension may be made with tablets and either a 1:1 mixture of Ora-Sweet® and Ora-Plus® or a 1:1 mixture of Ora-Sweet® SF and Ora-Plus®. Crush twelve 250 mg tablets in a mortar and reduce to a fine powder. Add small portions of chosen vehicle and mix to a uniform paste; mix while adding the vehicle in incremental proportions to almost 120 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 120 mL. Label “shake well” and “refrigerate”. Stable for 60 days (Allen, 1996). When diluted in 120 mL solution of cherry syrup concentrate diluted 1:4 with simple syrup, NF, it is stable 60 days refrigerated (preferred) or at room temperature (Nahata, 2004).Allen LV Jr and Erickson MA 3rd, "Stability of Acetazolamide, Allopurinol, Azathioprine, Clonazepam, and Flucytosine in Extemporaneously Compounded Oral Liquids," Am J Health Syst Pharm, 1996, 53(16):1944-9.8862208Nahata MC, Pai VB, and Hipple TF, Pediatric Drug Formulations, 5th ed, Cincinnati, OH: Harvey Whitney Books Co, 2004.
Oral: May be administered with food. May cause an alteration in taste, especially carbonated beverages. Short-acting tablets may be crushed and suspended in cherry or chocolate syrup to disguise the bitter taste of the drug; do not use fruit juices. Alternatively, submerge tablet in 10 mL of hot water and add 10 mL honey or syrup.
IM: IM administration is painful because of the alkaline pH of the drug; use by this route is not recommended.
IV: Direct IV injection is the preferred parenteral route of administration. Specific IV push rates are not provided in the manufacturer's labeling. However, an IV push rate of up to 500 mg over 3 minutes has been reported in a clinical trial (Mazur 1999). Additionally, a study to assess cerebrovascular reserve used a rapid IV push of up to 1 g over ≤1 minute (Piepgras 1990).
May be taken with food to decrease GI upset. May have additive effects with other folic acid antagonists. Some products may contain sodium.
Capsules, tablets: Store at controlled room temperature.
Injection: Store intact vials at 20°C to 25°C (68°F to 77°F). Store reconstituted solutions for 3 days under refrigeration at 2°C to 8°C (36°F to 46°F), or 12 hours at room temperature, 20°C to 25°C (68°F to 77°F).
Ajmaline: Sulfonamides may enhance the adverse/toxic effect of Ajmaline. Specifically, the risk for cholestasis may be increased. Monitor therapy
Alpha-/Beta-Agonists (Indirect-Acting): Carbonic Anhydrase Inhibitors may increase the serum concentration of Alpha-/Beta-Agonists (Indirect-Acting). Monitor therapy
Amantadine: Carbonic Anhydrase Inhibitors may increase the serum concentration of Amantadine. Monitor therapy
Amphetamines: Carbonic Anhydrase Inhibitors may decrease the excretion of Amphetamines. Monitor therapy
CarBAMazepine: Carbonic Anhydrase Inhibitors may increase the serum concentration of CarBAMazepine. Monitor therapy
Carbonic Anhydrase Inhibitors: May enhance the adverse/toxic effect of other Carbonic Anhydrase Inhibitors. The development of acid-base disorders with concurrent use of ophthalmic and oral carbonic anhydrase inhibitors has been reported. Management: Avoid concurrent use of different carbonic anhydrase inhibitors if possible. Monitor patients closely for the occurrence of kidney stones and with regards to severity of metabolic acidosis. Avoid combination
CycloSPORINE (Systemic): AcetaZOLAMIDE may increase the serum concentration of CycloSPORINE (Systemic). Monitor therapy
Dexketoprofen: May enhance the adverse/toxic effect of Sulfonamides. Monitor therapy
Diacerein: May enhance the therapeutic effect of Diuretics. Specifically, the risk for dehydration or hypokalemia may be increased. Monitor therapy
Flecainide: Carbonic Anhydrase Inhibitors may increase the serum concentration of Flecainide. Monitor therapy
Fosphenytoin-Phenytoin: Carbonic Anhydrase Inhibitors may enhance the adverse/toxic effect of Fosphenytoin-Phenytoin. Specifically, the risk for osteomalacia or rickets may be increased. Monitor therapy
Lithium: Carbonic Anhydrase Inhibitors may decrease the serum concentration of Lithium. Monitor therapy
Mecamylamine: Sulfonamides may enhance the adverse/toxic effect of Mecamylamine. Avoid combination
Mefloquine: May diminish the therapeutic effect of Anticonvulsants. Mefloquine may decrease the serum concentration of Anticonvulsants. Management: Mefloquine is contraindicated for malaria prophylaxis in persons with a history of convulsions. Monitor anticonvulsant concentrations and treatment response closely with concurrent use. Consider therapy modification
Memantine: Carbonic Anhydrase Inhibitors may increase the serum concentration of Memantine. Monitor therapy
MetFORMIN: Carbonic Anhydrase Inhibitors may enhance the adverse/toxic effect of MetFORMIN. Specifically, the risk of developing lactic acidosis may be increased. Monitor therapy
Methenamine: Carbonic Anhydrase Inhibitors may diminish the therapeutic effect of Methenamine. Management: Consider avoiding this combination. Monitor for decreased therapeutic effects of methenamine if used concomitant with a carbonic anhydrase inhibitor. Consider therapy modification
Mianserin: May diminish the therapeutic effect of Anticonvulsants. Monitor therapy
Opioid Analgesics: May enhance the adverse/toxic effect of Diuretics. Opioid Analgesics may diminish the therapeutic effect of Diuretics. Monitor therapy
Orlistat: May decrease the serum concentration of Anticonvulsants. Monitor therapy
Primidone: Carbonic Anhydrase Inhibitors may enhance the adverse/toxic effect of Primidone. Specifically, osteomalacia and rickets. Carbonic Anhydrase Inhibitors may decrease the serum concentration of Primidone. Monitor therapy
QuiNIDine: Carbonic Anhydrase Inhibitors may decrease the excretion of QuiNIDine. Monitor therapy
Salicylates: May enhance the adverse/toxic effect of Carbonic Anhydrase Inhibitors. Salicylate toxicity might be enhanced by this same combination. Management: Avoid these combinations when possible.Dichlorphenamide use with high-dose aspirin as contraindicated. If another combination is used, monitor patients closely for adverse effects. Tachypnea, anorexia, lethargy, and coma have been reported. Consider therapy modification
Sodium Bicarbonate: AcetaZOLAMIDE may enhance the adverse/toxic effect of Sodium Bicarbonate. Specifically, the risk of renal calculus formation may be increased. Monitor therapy
Sodium Phosphates: Diuretics may enhance the nephrotoxic effect of Sodium Phosphates. Specifically, the risk of acute phosphate nephropathy may be enhanced. Management: Consider avoiding this combination by temporarily suspending treatment with diuretics, or seeking alternatives to oral sodium phosphate bowel preparation. If the combination cannot be avoided, hydrate adequately and monitor fluid and renal status. Consider therapy modification
Trientine: Carbonic Anhydrase Inhibitor Diuretics may decrease the serum concentration of Trientine. Monitor therapy
May cause false-positive results for urinary protein with Albustix®, Labstix®, Albutest®, Bumintest®; interferes with HPLC theophylline assay and serum uric acid levels; may lead to false-negative aldosterone/renin ratio (ARR) (Funder 2016)
Frequency not defined.
Central nervous system: Ataxia, confusion, convulsions, depression, dizziness, drowsiness, excitement, fatigue, flaccid paralysis, headache, malaise, paresthesia
Dermatologic: Allergic skin reaction, skin photosensitivity, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria
Endocrine & metabolic: Electrolyte imbalance, growth retardation (children), hyperglycemia, hypoglycemia, hypokalemia, hyponatremia, metabolic acidosis
Gastrointestinal: Decreased appetite, diarrhea, dysgeusia, glycosuria, melena, nausea, vomiting
Genitourinary: Crystalluria, hematuria
Hematologic and oncologic: Agranulocytosis, aplastic anemia, leukopenia, thrombocytopenia, thrombocytopenic purpura
Hepatic: Abnormal hepatic function tests, cholestatic jaundice, fulminant hepatic necrosis, hepatic insufficiency
Local: Pain at injection site
Otic: Auditory disturbance, tinnitus
Renal: Polyuria, renal failure
Concerns related to adverse effects:
• CNS effects: Impairment of mental alertness and/or physical coordination may occur.
• Sulfonamide (“sulfa”) allergy: The FDA-approved product labeling for many medications containing a sulfonamide chemical group includes a broad contraindication in patients with a prior allergic reaction to sulfonamides. There is a potential for cross-reactivity between members of a specific class (eg, two antibiotic sulfonamides). However, concerns for cross-reactivity have previously extended to all compounds containing the sulfonamide structure (SO2NH2). An expanded understanding of allergic mechanisms indicates cross-reactivity between antibiotic sulfonamides and nonantibiotic sulfonamides may not occur or at the very least this potential is extremely low (Brackett 2004; Johnson 2005; Slatore 2004; Tornero 2004). In particular, mechanisms of cross-reaction due to antibody production (anaphylaxis) are unlikely to occur with nonantibiotic sulfonamides. T-cell-mediated (type IV) reactions (eg, maculopapular rash) are less well understood and it is not possible to completely exclude this potential based on current insights. In cases where prior reactions were severe (Stevens-Johnson syndrome/TEN), some clinicians choose to avoid exposure to these classes.
• Diabetes: Use with caution in patients with prediabetes or diabetes mellitus; may see a change in glucose control.
• Hepatic impairment: Use with caution in patients with hepatic dysfunction; in cirrhosis, avoid electrolyte and acid/base imbalances that might lead to hepatic encephalopathy.
• Respiratory acidosis: Use with caution in patients with respiratory acidosis; may worsen acidosis.
Concurrent drug therapy issues:
• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.
• Elderly: Use with caution in the elderly; may be more sensitive to side effects.
• Appropriate use: Increasing the dose does not increase diuresis and may increase the incidence of drowsiness and/or paresthesia; often results in a reduction of diuresis.
• IM administration: Painful because of the alkaline pH of the drug; use by this route is not recommended.
Intraocular pressure; serum electrolytes, periodic CBC with differential; monitor growth in pediatric patients
Pregnancy Risk Factor
Adverse events have been observed in animal reproduction studies. Limited data is available following the use of acetazolamide in pregnant women for the treatment of idiopathic intracranial hypertension (Falardeau 2013; Kesler 2013).
Pregnant women exposed to acetazolamide during pregnancy for the treatment of seizure disorders are encouraged to enroll themselves into the AED Pregnancy Registry by calling 1-888-233-2334. Additional information is available at aedpregnancyregistry.org
• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
• Patient may experience nausea, vomiting, change in taste, diarrhea, lack of appetite, blurred vision, fatigue, loss of strength and energy, or headache. Have patient report immediately to prescriber signs of lactic acidosis (fast breathing, tachycardia, abnormal heartbeat, vomiting, fatigue, shortness of breath, severe loss of strength and energy, severe dizziness, feeling cold, or muscle pain or cramps), signs of fluid and electrolyte problems (mood changes, confusion, muscle pain or weakness, abnormal heartbeat, severe dizziness or passing out, tachycardia, increased thirst, seizures, loss of strength and energy, lack of appetite, urinary retention or change in the amount of urine passed, dry mouth, dry eyes, or nausea or vomiting), vision changes, hearing impairment, tinnitus, burning or numbness feeling, hematuria, urinary retention, change in amount of urine passed, signs of a severe sulfonamide reaction (rash; red, swollen, blistered, or peeling skin; red or irritated eyes; mouth, throat, nose, or eye sores; fever, chills, or pharyngitis; cough that is new or worse; loss of strength and energy; any bruising or bleeding; or signs of liver problems like dark urine, fatigue, lack of appetite, upset stomach or stomach pain, light-colored stools, throwing up, or jaundice), or injection site pain or irritation (HCAHPS).
• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
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- Drug class: carbonic anhydrase inhibitor anticonvulsants
- Acetazolamide (AHFS Monograph)
- Acetazolamide Sodium (AHFS Monograph)
- Acetazolamide (FDA)
- Acetazolamide Capsules (FDA)
- Acetazolamide Tablets (FDA)
Other brands: Diamox