Overview of Idoxuridine for Cats

 Idoxuridine, also known by the names Stoxil®, Herplex®, Dendrid®, is often used for cats in the treatment of conjunctival and corneal disease associated with feline herpes virus.

 A virus is a packet of genetic material, often DNA, surrounded by a viral envelope or membrane. This virus is quite fragile when outside the body but is very damaging when allowed to thrive inside a body.

Once it enters a body, it latches onto a cell and inserts its own DNA into the cell. This DNA takes over the function of the cell and begins to reproduce itself rapidly.

In a short time, the cell becomes so full of viral particles that it bursts and releases more viruses throughout the body. Each of these new viral agents then repeats the process until the body is overwhelmed and illness develops.

Idoxuridine is a topical anti-viral agent. It inhibits viral growth by interfering with the virus’ production of DNA.

It was one of the first topical anti-viral agents developed. Like other anti-viral drugs, idoxuridine is a cytotoxic agent.

When applied to the eye idoxuridine is most effective against viruses affecting the conjunctiva, and corneal epithelium and stroma.

Idoxuridine 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 Idoxuridine

This drug is registered for use in humans only.

Human formulation: Stoxil®, Herplex®, Dendrid®, Various generic formulations, manufactured by compounding pharmacies.

Veterinary formulation: None

Uses of Idoxuridine for Cats

The primary use of idoxuridine is in the treatment of conjunctival and corneal disease associated with feline herpesvirus.

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

Precautions and Side Effects

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

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

The drug should not be used in pregnant or lactating animals.

Idoxuridine can be irritating to the eye, particularly to an injured eye.

Idoxuridine may interact with other medications. Consult your veterinarian to determine if other drugs your pet is receiving could interact with idoxuridine. Such drugs include topical boric acid ointments and corticosteroids.

How Idoxuridine is Supplied

Idoxuridine is available in a 0.1% ophthalmic solution in 2.5 ml and 5 ml bottles.

These solutions are manufactured upon demand by compounding pharmacies. The solution is somewhat unstable and should be stored in a refrigerator and protected from light.

Dosing Information of Idoxuridine for Cats

Medication should never be administered without first consulting your veterinarian.

The ideal dosage regimen for use in cats is not well defined. The most common recommendations are to apply the drug 4 to 8 times daily for 3 to 6 weeks. Generally has less stinging than other similar drugs. 

The end-point of therapy is often difficult to determine, because feline herpesvirus-1 readily becomes inactive, and signs may recur with termination of the drug. 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 pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.