What is cidofovir ophthalmic?
Cidofovir ophthalmic is a topical medication used in cats to treat viral infections of the eye, such as feline herpesvirus-1 (FHV-1). Cidofovir ophthalmic must be compounded by a veterinarian or a veterinary pharmacy into an eye drop solution for cats.
Its use in the treatment of FHV-1 in cats 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 do I give cidofovir ophthalmic to my cat?
- Your veterinarian will provide specific instructions for use in your cat.
- Administer the exact prescribed amount to your cat’s eye.
- Avoid contamination of the eye medication’s applicator tip. Do not allow the dropper tip to touch your animal’s eye or any other surface.
- If this medication spills onto your cat’s hair, clean it off with a damp cloth before your cat can lick it.
- Wait 5 to 10 minutes before applying any other eye medications.
- Do not give this medication if the solution becomes cloudy or if it appears to contain particulate matter.
Cidofovir ophthalmic is considered a hazardous drug, so it is essential to avoid accidental exposure.
- Wear gloves when handling the medication. Avoid contact with your skin, eyes, or gums.
- Do not handle the medication if you are pregnant or nursing.
- Avoid contact with the pet’s bodily fluids and waste for 5 days after administration.
- Wear chemotherapy-resistant protective gloves when cleaning urine, feces, or vomit.
- Do not allow your cat to lick your skin. If skin exposure occurs, wash thoroughly with soap and water.
This medication can take up to a few weeks before full effects are noted, but gradual improvements are usually noticeable after a few days.
What if I miss giving a dose to my cat?
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 or give extra doses.
Are there any potential side effects?
Cidofovir ophthalmic may cause the following side effects:
- Eye irritation, such as a mild stinging sensation or redness of the eyes
Serious adverse reactions may occur. If any of the following signs develop, stop giving cidofovir ophthalmic and contact your veterinarian immediately:
- Difficult or noisy breathing
- Lack of appetite
- Yellowing of the whites of the eyes
- Pain in the back or sides
- Increased urination
- Weakness
- Lethargy
- Limb pain
- Mouth sores
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 cidofovir ophthalmic in:
- Pets with hypersensitivity to the drug
- Pets that are breeding
- Pets with kidney disease
- Pets that are taking other medications that can damage the kidneys (nephrotoxic)
Are there any drug interactions I should be aware of?
Certain drugs can interact with systemic cidofovir, but their significance for ophthalmic administration in animals is unknown. 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 let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
- At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.
How do I store cidofovir ophthalmic?
- Cidofovir ophthalmic is typically stored in the refrigerator, protected from light and freezing. However, since this medication must be compounded, always follow the storage directions on the medication label.
- Keep the medication out of reach of children and pets. 
What should I do in case of an emergency?
An overdose of eye medication is unlikely but side effects or toxic effects can occur if your cat ingests it. If you suspect an overdose or 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.
