Methazolamide

Major Uses

Methazolamide is a carbonic anhydrase inhibitor and sulfonamide derivative used to treat certain types of glaucoma in dogs. It is most commonly used for open-angle glaucoma.

Methazolamide works by lowering intraocular pressure. It is not approved by the Food and Drug Administration for use in animals, but it is commonly prescribed for this purpose.

Common Precautions

Methazolamide may cause stomach upset. Giving the medication with food should help. Additionally, this medication may cause depression, sedation, excitement, or tremors. Bone marrow depression is also possible and can lead to bruising and abnormal bleeding. Other possible side effects associated with use of methazolamide include rashes, electrolyte imbalance, increased thirst, and increased or painful urination, and jaundice. Adjusting the time of administration may help prevent increased urination.

This drug is not for use in animals with severe kidney, liver, or lung disease. Methazolamide should also not be used in animals with Addison's disease or electrolyte imbalance. Caution is warranted in cases of gout or diabetes mellitus. Methazolamide should not be used for long periods in animals suffering from closed-angle glaucoma.

This drug is known to interact with a number of medications and supplements, including primidone, phenobarbital, quinidine, methotrexate, procainamide, and methenamine. Methazolamide may cause abnormally low blood potassium levels when used with amphotericin B, corticosteroids, aspirin, insulin, tricyclic antidepressants, corticotrophin, or digoxin. Softening of the bones may occur when used along with primidone or phenytoin. Methazolamide may cause abnormal laboratory results when protein levels are measured in the urine.

Methazolamide should not be used in animals with a known allergy or hypersensitivity to the drug. Overdose of methazolamide is a serious concern and can cause depression, vomiting, weakness, seizures, jaundice, and dehydration. Any known or suspected overdose should be reported to a veterinarian right away.

Storage

Methazolamide should be stored at room temperature, in a tightly-closed container, away from light. This medication should be kept out of the reach of children and animals.

Administration

Methazolamide is available in tablet form.

For the treatment of glaucoma, methazolamide is typically dosed at 2.5 to 5 mg/kg every 8 to 12 hours in dogs. In cats, the typical dose is 3 to 4 mg/kg twice daily. Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose of methazolamide is skipped, it should be taken as soon as possible. If it is almost time for the next dose, the missed dose should be skipped and a normal schedule should be resumed. It is important not to give two doses of this medication at once.