Trade and other names: Diamox
Functional classification: Diuretic
Carbonic anhydrase inhibitor. Acetazolamide, like other carbonic anhydrase inhibitors, produces a diuresis through inhibition of the uptake of bicarbonate in proximal renal tubules via enzyme inhibition. This action results in loss of bicarbonate in the urine and a diuresis. The action of carbonic anhydrase inhibitors results in urine loss of bicarbonate, alkaline urine, and water loss.
Indications and Clinical Uses
Acetazolamide is rarely used as a diuretic any longer. There are more potent and effective diuretic drugs available such as the loop diuretics (furosemide).
Acetazolamide, like other carbonic anhydrase inhibitors, is used primarily to lower intraocular pressure in animals with glaucoma. Methazolamide is used more often than acetazolamide for this purpose, and other treatment regimens are now used more often than carbonic anhydrase inhibitors. Acetazolamide, like other carbonic anhydrase inhibitors, is sometimes used to produce more alkaline urine for management of some urinary calculi.
Adverse Reactions and Side Effects
Acetazolamide can potentially produce hypokalemia in some patients. Significant bicarbonate loss can occur with repeated administration. In dogs, a respiratory reaction has been observed, which is attributed to respiratory acidosis.
Contraindications and Precautions
Do not use in patients with acidemia. Use cautiously in any animal sensitive to sulfonamides.
Acetazolamide will produce alkaline urine, which may affect clearance of some drugs. Alkaline urine may potentiate the effects of some antibacterial drugs (e.g., macrolides and quinolones).
Instructions for Use
Acetazolamide, in combination with other agents, is usually used to decrease intraocular pressure in the treatment of glaucoma. Acetazolamide has been used to produce alkaline urine to prevent formation of some urinary calculi. However, unless there is supplementation with bicarbonate, the urine alkalinization will not be sustained with repeated administration.
Patient Monitoring and Laboratory Tests
Monitor patient’s ocular pressure when used to treat glaucoma.
Acetazolamide is available in 125-and 250-mg tablets. Stability and Storage Stable if stored in tight containers. Compounded solutions are stable at least 60 days.
Small Animal Dosage
• Glaucoma: 5-10 mg/kg q8-12h PO.
• Other diuretic uses: 4-8 mg/kg q8-12h PO.
• 7 mg/kg, q8h, PO.
Large Animal Dosage
No dose has been reported for large animals.