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Trifluridine (Viroptic)

An antiviral eye drop used to treat herpes simplex keratitis (epithelial dendritic ulcers). One of two main topical antivirals for ocular HSV infection.

Drug Class: Antiviral

7 min read

Trifluridine (brand name Viroptic) is a topical antiviral eye drop used to treat epithelial herpes simplex virus (HSV) keratitis - the dendritic and geographic ulcers that develop on the corneal surface during active herpes infection. It is one of two main agents used for this purpose; the other is ganciclovir gel (Zirgan). Trifluridine has been a workhorse topical antiviral in the United States for decades, although many practices now favor ganciclovir gel because of its less frequent dosing and better corneal tolerance.

Key Takeaways

  • Used for active epithelial HSV keratitis - dendritic and geographic ulcers; not for stromal disease alone
  • Dosed every 2 hours while awake during active infection, up to a maximum of 9 drops per day
  • Most cases resolve in 7-14 days with adherent treatment
  • Toxicity to the corneal surface with prolonged use; reassess if no improvement after 7 days or no full re-epithelialization by 14 days, and avoid continuous use beyond 21 days
  • Not effective against established stromal keratitis or uveitis alone - those forms typically need oral antivirals plus topical steroids under careful supervision

How It Works

Trifluridine is a thymidine analog that, after intracellular phosphorylation, becomes incorporated into viral DNA, halting replication. Unlike acyclovir-family agents, its activity is not dependent on viral thymidine kinase, so it can retain activity against some thymidine-kinase-deficient resistant strains.

The drug is rapidly cleared from the tear film, which is why frequent dosing is required to maintain therapeutic concentrations on the corneal surface.

Common Uses

  • Epithelial HSV keratitis - dendritic and geographic ulcers; the primary indication
  • Reactivation episodes - used during each acute attack
  • Adjunctive use during long-term management of recurrent disease (with oral antivirals as the maintenance therapy)

Not Indicated For

  • Stromal keratitis - disease in the deeper cornea is treated with oral acyclovir family agents and carefully managed topical steroids; topical trifluridine alone is inadequate
  • HSV uveitis or retinitis - systemic treatment is required
  • Prophylaxis after corneal transplant in HSV history - oral antivirals are standard

How to Use

  • Active infection dosing: One drop in the affected eye(s) every 2 hours while awake, up to a maximum of 9 drops per day, until the ulcer reepithelializes - usually 7-14 days
  • Tapering: After reepithelialization, dose is typically reduced (one drop every 4 hours, 5 drops per day) for an additional 7 days
  • Duration guardrails: reassess if no improvement after 7 days or no full re-epithelialization by 14 days; continuous use beyond 21 days should be avoided due to corneal toxicity
  • Storage: Keep refrigerated, 2-8°C (36-46°F), per the Viroptic label
  • Multiple drops: Wait at least 5 minutes between different eye drops
  • Contact lenses: Do not wear during treatment

What to Expect

Symptom Improvement

  • Pain and photophobia begin to improve within 2-4 days
  • The dendritic ulcer fades over 5-10 days
  • Reepithelialization (full healing of the surface) over 7-14 days
  • Vision improves with healing, though some patients have residual subepithelial haze or scarring

Demanding Schedule

  • The every-2-hour-while-awake dosing is demanding and requires patient commitment
  • Set alarms; carry the bottle
  • Missed doses prolong the course and may lead to recurrence

Side Effects

Local

  • Stinging or burning on instillation - common
  • Punctate epithelial keratopathy - small dots of corneal staining from drug toxicity
  • Conjunctival hyperemia and mild eyelid swelling
  • Allergic blepharoconjunctivitis with prolonged use
  • Punctal occlusion or stenosis in chronic users
  • Corneal toxicity - the reason prolonged continuous use beyond 21 days should be avoided

Systemic

  • Negligible - minimal systemic absorption from topical use

Trifluridine vs. Ganciclovir Gel

The two main topical antivirals for HSV keratitis differ in important ways:

Feature Trifluridine Ganciclovir gel
Concentration 1% solution 0.15% gel
Dosing during active infection Every 2 hr awake, max 9 drops/day 5× daily
Dosing after reepithelialization 5× daily for 7 days 3× daily for 7 days
Tolerance Stings; corneal toxicity with prolonged use Better tolerated
Mechanism Thymidine analog (TK-independent) Guanosine analog (requires viral TK)
Resistance Effective against TK-deficient HSV Susceptible to TK-deficient resistance
Available since 1980 2009 (US)
Cost Generic available, but U.S. supply and price can vary Brand more expensive

For many patients, ganciclovir gel has become preferred because of more convenient dosing and less corneal toxicity. Trifluridine remains useful in TK-deficient resistant cases and where cost is a priority.

Adjunctive Therapy

Mechanical Debridement

For dendritic ulcers, gentle mechanical debridement of the loose epithelium with a sterile cotton swab is often performed in addition to antiviral therapy and may speed healing.

Oral Antivirals

  • Valacyclovir, acyclovir, or famciclovir - typically used for stromal disease, deep involvement, or recurrent prophylaxis
  • The HEDS trials established the value of oral antivirals in many forms of HSV eye disease

Topical Steroids

  • Avoided in active epithelial disease - steroids can worsen dendritic ulcers
  • Used carefully in stromal keratitis under supervision, often combined with oral antiviral coverage

Cycloplegic Drops

  • For comfort and to reduce ciliary spasm with associated iridocyclitis

Frequently Asked Questions

Why every 2 hours? That seems impossible to maintain.

The drug is rapidly cleared from the tear film and the virus replicates quickly. Less frequent dosing can fail to maintain effective concentrations on the cornea. The dosing is designed to keep the viral pressure low while staying within the labeled maximum of 9 drops per day.

Will my eye go back to normal?

Most epithelial HSV ulcers heal completely with topical antiviral treatment. Some patients are left with mild subepithelial haze, particularly after multiple recurrent episodes. Recurrent stromal involvement can produce permanent scarring and vision loss; long-term oral antiviral prophylaxis can reduce recurrence frequency.

Can I use the drop indefinitely?

No. Continuous use beyond roughly 21 days should be avoided because of corneal toxicity. If there is no improvement after 7 days, or if the ulcer has not fully re-epithelialized by 14 days, your doctor will reassess - sometimes the agent is switched, oral antivirals are added, or the diagnosis is reconsidered.

Why am I being prescribed both eye drops and oral antivirals?

For some patients with stromal involvement, recurrent disease, or in special situations (corneal transplant, immunocompromised), oral antiviral therapy is added. The drops treat the active surface ulcer; the oral medication addresses deeper or systemic spread and reduces future recurrence risk.

Can I wear contact lenses during treatment?

No. Contact lens wear during active herpes keratitis is contraindicated - the lens itself can harbor the virus and prolong infection, and toxicity from the drop is exaggerated when contact lenses are worn. Resume contact lens use only after full healing and clearance from your doctor.

How does trifluridine differ from oral acyclovir?

Trifluridine is a topical drop that works directly on the corneal surface; oral acyclovir (and its prodrug valacyclovir) are systemic agents. Topical drops give high local concentration with minimal systemic exposure; oral agents are needed when the disease is in the corneal stroma, the inside of the eye, or when ongoing recurrence prevention is the goal.

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