Idoxuridine is a topical antiviral cytotoxic agent that is prescribed to treat cats afflicted with corneal or conjunctival diseases attributed to feline herpes virus. This drug is not typically used in dogs, as canine herpes virus is not a commonly occurring eye disease.

Pharmacology of Idoxuridine

Idoxuridine was one of the first topical antiviral agents developed. Its primary mechanism of action is to interfere with the DNA production of the virus. The drug effectively stunts the growth of the virus, which prevents the virus from multiplying, while weakening it and making it more susceptible and eventually leading to the death of the virus.

Idoxuridine Precautions

Idoxuridine should not be administered to a veterinary patient that has exhibited an allergic reaction to the drug previously. This medication should also be avoided in pregnant or lactating animals.

Idoxuridine is a powerful antiviral agent and when applied to the eye, it may cause some irritation. In cases that involve physical damage or injury to the eye, caution must be used. Please note that dosing during the first several days of treatment is quite frequent and requires diligence on the part of the owner. After the initial treatment period, dosing frequency may allow a longer length of time between doses.

Ophthalmic medications are sterile products. It is important to keep the tip of the bottle or ointment tube from contact.

Possible Side Effects of Idoxuridine

Idoxuridine is safe and effective for use in cats suffering from ophthalmic issues associated with feline herpes virus. However, some cats may experience side effects after receiving treatment. The most common possible side effects reported include sensitivity to light, mild itchiness, swelling, redness and general irritation. In most cases, these side effects eventually decrease as the body adjusts to the medication and dosing frequency becomes farther apart.

If the cat experiences symptoms of an allergic reaction, such as difficulty breathing, swelling of the face, lips or tongue, severe itchiness and skin rash, contact the veterinarian immediately.

Idoxuridine Contraindications

Idoxuridine may cause an unwanted reaction when used with other medications. Therefore, it is very important to discuss the cat’s current drug regimen with the veterinarian before treatment begins. Such drugs to avoid include certain corticosteroids and topical ointments containing boric acid.

How is Idoxuridine Supplied?

Idoxuridine is available only with a prescription from a veterinarian. It is compounded in either an ophthalmic ointment or in an ophthalmic solution. Because this medication is sensitive to light and heat, the ophthalmic drops need to be stored in the refrigerator when not being administered, though the ointment is not as sensitive to temperature as the solution. Since this medication is fighting an infection in the body, it is very important to complete the entire course of treatment in order to reduce the risk of a relapse. It is generally continued 4-7 days after resolution of symptoms.

Author: Giano Panzarella