Idoxuridine is an anti-herpesvirus antiviral drug

Antiviral drug

Antiviral drugs are a class of medication used specifically for treating viral infections. Like antibiotics for bacteria, specific antivirals are used for specific viruses...

.

It is a nucleoside analogue, a modified form of deoxyuridine

Deoxyuridine

Deoxyuridine is a compound and a nucleoside. It is similar in chemical structure to uridine, but without the 2'-hydroxyl group.Idoxuridine and Trifluridine are variants of deoxyuridine used as antiviral drugs...

, similar enough to be incorporated into viral DNA replication

DNA replication

DNA replication is a biological process that occurs in all living organisms and copies their DNA; it is the basis for biological inheritance. The process starts with one double-stranded DNA molecule and produces two identical copies of the molecule...

, but the iodine

Iodine

Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....

 atom added to the uracil

Uracil

Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine, cytosine, and guanine. In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine.Uracil is a common and...

 component blocks base pair

Base pair

In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...

ing. It is used only topically due to cardiotoxicity.

Clinical use

Idoxuridine is mainly used topically to treat herpes simplex

Herpes simplex

Herpes simplex is a viral disease caused by both Herpes simplex virus type 1 and type 2 . Infection with the herpes virus is categorized into one of several distinct disorders based on the site of infection. Oral herpes, the visible symptoms of which are colloquially called cold sores or fever...

 keratitis

Keratitis

Keratitis is a condition in which the eye's cornea, the front part of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.-Types:...

. Epithelial lesions, especially initial attacks presenting with a dendritic ulcer, are most responsive to therapy, while infection with stromal involvement are less responsive. Idoxuridine is ineffective against herpes simplex virus type 2 and varicella-zoster.

Formulations and dosage

Idoxuridine is available as either a 0.5% ophthalmic ointment or as a 0.1% ophthalmic solution

Solution

In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

. The dosage of the ointment is every 4 hours during day and once before bedtime. The dosage of the solution is 1 drop in the conjunctival sac

Conjunctiva

The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...

 hourly during the day and every 2 hours during the night until definitive improvement, then 1 drop every 2 hours during the day and every 4 hours during the night. Therapy is continued for 3-4 days after healing is complete, as demonstrated by fluorescein

Fluorescein

Fluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications....

staining.