Overview of Vidarabine (Vira-A®) for Cats

Vidarabine, commonly known as Vira-A®, is used for the treatment of conjunctival and corneal disease associated with feline herpes virus in cats.

Vidarabine is an antiviral agent used to combat viruses that affect the conjunctiva, corneal epithelium and stroma.

Vidarabine works by interfering with a virus’ DNA replication. It belongs to a class of drugs called nucleosides.

Vidarabine is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.

This drug is not approved for use in animals by the Food and Drug Administration (FDA), but it is prescribed legally by veterinarians as an extra-label drug.

Brand Names and Other Names of Vidarabine

This drug is registered for use in humans only.

Human formulation: Vira-A® (Parke-Davis)

Veterinary formulation: None

Uses of Vidarabine for Cats

The primary use of vidarabine is in the treatment of conjunctival and corneal disease associated with feline herpes virus.

Because canine herpesvirus has not been identified as a common eye disease in dogs, the drug is not often used in dogs.

Precautions and Side Effects

While generally safe and effective when prescribed by a veterinarian, vidarabine can potentially cause side effects in some animals.

Vidarabine should not be used in animals with known hypersensitivity or allergy to the drug.

The drug should be avoided in pregnant cats. Although its effects in lactating animals have not been defined, the drug should also be avoided in these animals.

Stinging upon application, tearing, and conjunctival hyperemia (redness to the eyes) may occur.

No drug interactions have been noted.

How Vidarabine is Supplied

Vidarabine is available as a 3% ophthalmic ointment in a 3.5 gram tube. The drug is currently only available as generic ointments, manufactured by compounding pharmacies.

Dosing Information of Vidarabine for Cats

Medications should never be administered without first consulting your veterinarian.

While the ideal dosage regimen is not well defined, the most common recommendations are to apply the drug 4 to 5 times daily for 3 to 6 weeks. At a minimum, treatment is continued for one week after signs of disease have resolved.

The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your cat feels better, the entire treatment plan should be completed to decrease the likelihood of relapse.