Herplex0.1%

Herplex is a topical antiviral agent indicated for the treatment of herpes simplex keratitis (dendritic corneal ulcers) caused by herpes simplex virus infection of the eye.

• Established/approved use: Epithelial (dendritic) herpes simplex keratitis, where Herplex acts on actively replicating virus within infected corneal epithelial cells.
• Limited/adjunctive use: Herplex has limited efficacy in deep stromal herpetic keratitis when there is no epithelial (dendritic) involvement, and is generally not used alone in that setting.
• Not indicated for bacterial, fungal, or other viral eye infections; Herplex has no proven benefit outside herpes simplex epithelial keratitis, and unnecessary use should be avoided.

Each ophthalmic dose of Idoxuridine contains Idoxuridine as the active pharmaceutical ingredient, formulated as a sterile ophthalmic solution (commonly 0.1% w/v) for topical use in the eye, with pharmaceutical excipients such as buffering and preservative agents.

Herplex is a synthetic pyrimidine nucleoside analog with antiviral activity, structurally related to thymidine. It was one of the first antiviral agents developed and is used topically in the eye for herpes simplex viral infections of the cornea.

Herplex is formulated as a sterile ophthalmic solution for local application to the eye. It is not intended for systemic use and is not effective against non-herpetic ocular infections.

Herplex belongs to the class of ophthalmic antiviral agents (pyrimidine nucleoside analogs), used specifically for topical treatment of herpetic eye infections.

Idoxuridine is a thymidine analog that is phosphorylated intracellularly and incorporated into viral (and, to a lesser extent, host) DNA in place of thymidine. This incorporation results in the formation of faulty, functionally defective DNA, which inhibits viral replication and disrupts normal viral DNA synthesis.

Because Idoxuridine interferes with DNA synthesis in actively dividing cells, it is most effective against actively replicating herpes simplex virus in the corneal epithelium (dendritic ulcers), and is less effective once the virus has moved into the deeper corneal stroma.

Following topical ophthalmic administration, systemic absorption of Idoxuridine is minimal.

Herplex ophthalmic solution should be administered as follows:

• Wash hands thoroughly before use.
• Tilt the head back, gently pull down the lower eyelid to form a small pocket, and instill the prescribed number of drops into the eye without touching the dropper tip to the eye or eyelid.
• Close the eye gently for 1-2 minutes and apply light pressure at the inner corner of the eye (near the nose) to reduce systemic drainage.
• Avoid wearing contact lenses during treatment.
• Use only in the eye(s) prescribed by the physician and follow the exact frequency and duration prescribed.

Corticosteroids (topical ophthalmic): Concurrent use of topical corticosteroids with Herplex in the presence of active herpes simplex keratitis may mask or worsen the infection and increase the risk of corneal complications; corticosteroids should generally be avoided or used only under close ophthalmologist supervision in patients being treated with Herplex.

Boric acid-containing eye preparations: Concomitant use with boric acid-containing ophthalmic products may cause a precipitate to form; such combinations should be avoided.

Because Herplex is applied topically with minimal systemic absorption, clinically significant systemic drug interactions are not well established; however, other topical ophthalmic products should be spaced apart and used only as directed by a physician.

Side effects of Herplex are generally local, affecting the eye:

• Local irritation, burning, stinging, or itching of the eye
• Photophobia (sensitivity to light)
• Pain in or around the eye
• Allergic reactions such as eyelid swelling (edema), redness, or follicular conjunctivitis
• Punctate defects of the corneal epithelium
• With prolonged use: corneal clouding, small stromal opacities, or delayed corneal wound healing

Patients should notify their physician promptly if irritation worsens, if vision changes occur, or if the eye condition does not improve as expected.

There are no well-controlled studies of Herplex in pregnant women. Herplex is applied topically to the eye with minimal systemic absorption; however, as a nucleoside analog with demonstrated effects on DNA synthesis, it should be used in pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus. Use during pregnancy only under direct medical supervision.

It is not known whether topically applied Herplex is excreted in human milk in clinically significant amounts. Caution is advised, and a physician should be consulted before use of Herplex during breastfeeding.

Herplex should be used only under the supervision of an ophthalmologist, with regular follow-up eye examinations during treatment.

• Herplex has limited efficacy in deep stromal keratitis without epithelial (dendritic) involvement.
• Herplex is not effective against bacterial, fungal, or non-herpetic viral eye infections; secondary bacterial or fungal infection should be ruled out or treated appropriately if suspected.
• Prolonged or excessive use may cause corneal toxicity, including punctate defects and stromal clouding; do not exceed the prescribed frequency or duration of treatment.
• Avoid concurrent use of topical corticosteroids unless specifically directed by an ophthalmologist (see Interactions).
• Discontinue and consult a physician if signs of hypersensitivity or worsening ocular irritation occur.
• Avoid contact lens use during treatment.
• Take Herplex exactly as prescribed by your physician; do not stop, extend, skip doses, or share this medicine with others without medical advice.

Accidental excessive or prolonged use of Herplex ophthalmic solution may increase the risk of corneal toxicity (clouding, punctate defects) or local irritation. If Herplex is accidentally ingested, or if excessive instillation or a severe adverse reaction occurs, seek immediate medical attention or contact a poison control center; do not attempt specific home treatment.

Store Herplex ophthalmic solution in a refrigerator (2°C-8°C), protected from light. Do not freeze. Keep the container tightly closed, discard any remaining solution after the treatment course as advised by the pharmacist, and keep out of reach of children.

Pediatric use: Herplex may be used in children for herpes simplex keratitis only under direct ophthalmologist supervision; safety and efficacy of specific dosing regimens in children have not been as well established as in adults, and close monitoring is required.

Elderly: No specific dose adjustment is generally required for elderly patients using Herplex ophthalmically; standard precautions and regular monitoring apply.

Renal/hepatic impairment: Given minimal systemic absorption after topical ophthalmic use, specific dose adjustment for renal or hepatic impairment is not well established or generally considered necessary for Herplex.

Pregnancy and lactation: See Pregnancy and Lactation section.

Treatment with Herplex is typically continued until definite improvement is seen (usually within 3-5 days), and then continued for a further 3-5 days after complete corneal healing is confirmed by an ophthalmologist. Total duration of treatment generally should not exceed approximately 21 days due to the risk of corneal toxicity with prolonged use.

Ophthalmic antiviral; pyrimidine nucleoside analog (thymidine analog) — Idoxuridine class.

Idoxuridine is incorporated into replicating viral (and host) DNA in place of thymidine, producing defective, non-functional DNA and thereby inhibiting herpes simplex viral replication in infected corneal epithelial cells.

Herplex may be used in pediatric patients for herpes simplex (dendritic) keratitis, but only under direct ophthalmologist supervision, as safety and efficacy of specific pediatric dosing regimens are not as well established as in adults; close monitoring for local toxicity is recommended.