Acetazolamide
N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)acetamide
Also known as: Diamox · Acetazolamida · Acetazolamidum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Structured calculator evidenceAdjunctive therapy for treatment of glaucoma (extra-label)
- q8-12h
NA
Governing clinical context (2)
- ■ The most common side effect of this drug is stomach upset; giving with food may help reduce this effect.
- Acetazolamide tablets or unreconstituted powder for injection should be stored at room temperature of 20°C to 25°C (68°F-77°F) in a tightly closed container.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Acetazolamide is a systemic carbonic anhydrase inhibitor primarily used in veterinary medicine to reduce intraocular pressure in the management of glaucoma. It may also be used as an adjunctive treatment for metabolic alkalosis or certain seizure disorders.
Clinical Pearl: While effective for glaucoma, topical carbonic anhydrase inhibitors (like dorzolamide or brinzolamide) are generally preferred in modern veterinary practice due to significantly fewer systemic side effects.
Mechanism of action
Acetazolamide reversibly inhibits the enzyme carbonic anhydrase.
- In the eye: Inhibits carbonic anhydrase in the ciliary processes → decreases production of bicarbonate → reduces fluid transport and aqueous humor secretion → lowers intraocular pressure (IOP).
- In the kidneys: Inhibits carbonic anhydrase in the proximal renal tubules → decreases reabsorption of bicarbonate, sodium, and potassium → promotes alkaline diuresis and can cause mild metabolic acidosis.
Safety & warnings
Contraindications
- Hepatic failure
- Renal failure
- Severe pulmonary obstruction
- Hyponatremia
- Hypokalemia
- Hyperchloremic acidosis
Adverse effects
- Polyuria
- Polydipsia
- Metabolic acidosis
- Hypokalemia
- Vomiting
- Diarrhea
- Lethargy
- Panting (especially in dogs)
Precautions
Monitor electrolytes closely, especially potassium, during prolonged therapy. Use with extreme caution in patients with respiratory acidosis or conditions predisposing to electrolyte imbalances. Do not use in patients with severe hepatic or renal impairment.
Drug interactions
Hypokalemia induced by acetazolamide may increase the risk of digoxin toxicity.
Concurrent use increases the risk of severe hypokalemia.
Increased risk of salicylate toxicity and severe metabolic acidosis.
Alkalinization of urine by acetazolamide may increase the excretion of phenobarbital, potentially lowering its efficacy.
Monitoring
- Intraocular pressure (IOP)
- Serum electrolytes (especially potassium and sodium)
- Acid-base status (blood gases)
- Hydration status
Pharmacokinetics
Half-life
Absorption
Well absorbed from the gastrointestinal tract after oral administration.
Distribution
Distributes widely throughout the body, including the central nervous system and eyes. Highly bound to plasma proteins.
Metabolism
Not significantly metabolized in most species.
Elimination
Excreted primarily unchanged in the urine via tubular secretion.
Overdose
Overdosage may result in severe metabolic acidosis, hypokalemia, hyponatremia, and dehydration. Treatment consists of supportive care, including intravenous fluids to correct dehydration and electrolyte imbalances, and monitoring of acid-base status.
Available products
Formulations
- 250 mg tablets
- 250 mg capsules
Human-labeled
- Diamox 250 mg tablets
- Diamox SR 250 mg capsules
Regulatory status
POM (Prescription Only Medicine)
POM (Prescription Only Medicine)
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store at room temperature (15-30°C) in a tightly closed container, protected from light and moisture.
Client information
Acetazolamide is used to decrease pressure inside the eye for pets with glaucoma.
- Ensure your pet always has access to fresh drinking water, as this medication will increase urination.
- May cause stomach upset; giving with food can help.
- Contact your veterinarian if you notice severe weakness, lethargy, vomiting, or rapid breathing, as these could be signs of low potassium or changes in blood acidity.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.