Dorzolamide Ophthalmic

What is dorzolamide?

Dorzolamide (brand names: Trusopt®, Cosopt®) is an antiglaucoma medication used to treat increased pressures of the eye (ocular hypertension). Its use in cats, dogs, and horses to treat glaucoma is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is dorzolamide given?

• Dorzolamide is given in the form of a liquid drop applied directly to the eye.
• Wash your hands before administering this medication.
• Do not touch the tip of the dropper to the surface of the eye or any other surface.
• Give this medication at least 5 minutes apart from other medications used in the eye.

This medication should take effect within 1 to 2 hours; however, effects may not be noted outwardly, so laboratory tests may be needed to evaluate this medication’s effectiveness.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects?

Dorzolamide may cause the following side effects:

• Stinging sensation upon application to the eye
• Eye inflammation, characterized by eye redness, watery eyes, and light sensitivity
• Dry eyes
• Runny nose
• Nausea
• Vomiting

Serious adverse reactions may occur. If any of the following signs develop, stop giving dorzolamide and contact your veterinarian immediately:  

• A cloudy or blue eye
• Difficulty breathing (allergic reaction)
• Fever
• Skin rash

Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.  

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately.  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?

DO NOT USE dorzolamide in pets that:

• Are allergic to it or allergic to sulfonamides

USE WITH CAUTION in pets that:

• Have kidney disease
• Are pregnant or nursing

Are there any drug interactions I should be aware of?

There are no documented drug interactions with dorzolamide. Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• Your veterinarian will need to monitor eye pressure regularly to ensure that dorzolamide is working.
• Monitor your pet at home for serious side effects.

How do I store dorzolamide?

• Store at room temperature.
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.

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. Be prepared to provide information about the product and your pet's weight and symptoms.