Which medications in the drug class Antiviral agents are used in the treatment of Herpes Simplex Virus (HSV) Keratitis?

Updated: Jan 18, 2019
  • Author: Jim C Wang (王崇安), MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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Answer

Antiviral agents

These agents inhibit herpes simplex virus (HSV) replication. Treatment of viral infections begins with mechanical debridement of the involved rim along with a rim of normal epithelium. This is followed by the topical instillation of antiviral medications (eg, trifluridine, ganciclovir). [41]

Trifluridine ophthalmic solution 1% (Viroptic)

A structural analogue of thymidine, this agent inhibits viral DNA polymerase. Viroptic has better penetration through the cornea and greater efficacy (95% heal rate) than other topical agents. If no response occurs in 7-14 days, consider other treatments.

Valacyclovir (Valtrex)

Valacyclovir is a prodrug that is rapidly converted to the active drug acyclovir. It produces a greater serum concentration of acyclovir with smaller oral dosing. Valacyclovir is more expensive than acyclovir but can be as effective with a more convenient dosing regimen. [19] The optimal dose for ocular disease has not been determined.

Famciclovir (Famvir)

This agent is a prodrug that, when biotransformed into its active metabolite, penciclovir, may inhibit viral DNA synthesis/replication. It has been used successfully in the suppression of genital herpes. Its efficacy in HSV keratitis currently is under study.

Acyclovir (Zovirax)

Acyclovir is a synthetic guanosine analogue that requires activation by viral thymidine kinase. The activated acyclovir triphosphate, concentrated 50-100 times in HSV-infected cells, suppresses viral replication by preferentially inhibiting viral DNA polymerase, serving as a DNA chain terminator and inducing irreversible binding between polymerase enzyme and the interrupted DNA chain.

Acyclovir is a potent inhibitor of viral growth with minimal toxicity to uninfected epithelial cells. Oral acyclovir at a dose of 2 g/day for 10 days has been reported to be as effective as topical agents for epithelial keratitis, with the advantage of no ocular toxicity.

Ganciclovir ophthalmic gel 0.15% (Zirgan, Vitrasert)

This agent is an acyclic nucleoside analogue of 2'deoxyguanasine. It phosphorylates first to monophosphate form by a viral-encoded protein kinase homologue, and then to diphosphate and triphosphate forms by cellular kinases. This allows for greater concentration of ganciclovir in virus-infected cells, possibly because of preferential phosphorylation of this agent in infected cells.

Ganciclovir is thought to inhibit HSV replication by competitive inhibition of viral DNA polymerases and by incorporating itself into viral DNA, causing termination of viral DNA elongation. Like acyclovir, ganciclovir is virostatic and exerts its effect only on replicating virus.


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