By Kayla Hyland, DVM; Rania Gollakner, BS, DVM, MPH

What is acetazolamide?

Acetazolamide (brand name: Diamox®) is a diuretic and antiglaucoma agent, used primarily to treat glaucoma (increased eye pressure), syringomyelia (cyst that affects the nervous system), and metabolic alkalosis.

Its use in cats and dogs to treat glaucoma, syringomyelia, or metabolic alkalosis is “off label” or “extra label”. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is acetazolamide given?

Acetazolamide is given by mouth in the form of a tablet, capsule, or compounded liquid. Give this medication with food as stomach upset is the most common side effect, and giving with food may reduce this effect.

This medication should take effect within 1 to 2 hours; however, effects may not be obvious and so laboratory tests may need to be done to evaluate this medication’s effectiveness.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember; however, if it is close to time for the next dose, skip the dose you missed, give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Possible side effects include gastrointestinal upset, central nervous system effects such as sleepiness, weakness, or excitement; blood effects such as low blood cell counts; kidney effects such as increased drinking, crystal formation, or urination problems; electrolyte effects; high blood sugar; liver effects; skin effects such as a rash; and allergic reactions.

This medication should be used with extreme caution in pregnant and nursing animals, as veterinary safety information is limited for this medication and its effects are unknown.

This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Acetazolamide should not be used in pets with severe liver, kidney, or adrenal disease, certain electrolyte abnormalities (such as low sodium or potassium levels or high chloride levels), or obstructive lung disease. Long-term use is not recommended in pets with non-congestive, angle-closure glaucoma. It should be used with caution in pets with significant respiratory acidosis or pets with pre-existing blood abnormalities.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with acetazolamide: aspirin, cyclosporine, digoxin, insulin, methenamine compounds, phenobarbital, procainamide, quinidine, tricyclic antidepressants, or any medications that affect potassium levels, such as corticosteroids, amphotericin B, corticotropin, or other diuretics.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

While using this medication, your veterinarian will monitor your pet’s electrolytes and blood cell counts. Your veterinarian may take a baseline complete blood count before starting your pet on this medication. If used for glaucoma, your pet’s eye pressure will be monitored. If used for alkalosis, blood gases will be monitored.

Monitor your pet for side effects. If unusual panting, fast breathing, weakness, difficulty walking, behavior changes, shaking, or seizures occur, contact your veterinary office immediately.

How do I store acetazolamide?

Acetazolamide tablets should be stored at room temperature. Compounded liquid medications are usually stored in the refrigerator or at room temperature, away from light, but these recommendations can vary depending on the compounding pharmacy. Follow the directions provided on the label.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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