Ganciclovir Gel (Zirgan)

Ganciclovir 0.15% ophthalmic gel (brand name Zirgan) is a topical antiviral used to treat epithelial herpes simplex virus (HSV) keratitis - the dendritic and geographic ulcers that develop during active herpes infection of the cornea. It is one of two main agents used for this purpose; the other is trifluridine. Ganciclovir gel is preferred at many practices because of more convenient dosing and better corneal tolerance.

How It Works

Ganciclovir is a guanosine analog. It is selectively monophosphorylated by viral thymidine kinase in HSV-infected cells; host cellular kinases then add the second and third phosphates. The active triphosphate is incorporated into viral DNA and terminates replication. The gel formulation provides extended contact with the corneal surface, which permits a less frequent dosing schedule than the older trifluridine 1% solution.

Common Uses

• Epithelial HSV keratitis - dendritic and geographic ulcers; the primary indication
• Recurrent episodes - used during each acute attack
• Approved for adults and children ≥2 years

Not Indicated For

• Stromal keratitis - typically treated with oral acyclovir family agents and carefully managed topical steroids
• HSV uveitis or retinitis - systemic treatment is required
• Long-term prophylaxis - oral valacyclovir or acyclovir is the standard for ongoing recurrence prevention

How to Use

• Active infection dosing: One drop in the affected eye 5 times daily (approximately every 3 hours while awake) until the corneal ulcer heals - typically 7-10 days
• Maintenance after reepithelialization: 3 times daily for 7 days after healing
• Storage: Store at room temperature (15-25°C / 59-77°F); do not freeze
• Multiple drops: Wait at least 5 minutes between different eye drops
• Contact lenses: Do not wear during treatment

What to Expect

• Pain and photophobia improve within 2-4 days
• The dendritic ulcer fades over 5-10 days
• Reepithelialization in 7-10 days for most patients
• Less stinging on instillation than trifluridine
• Less corneal toxicity over the course of treatment

Side Effects

Local

• Mild blurred vision transiently after instillation (the gel temporarily clouds the tear film)
• Conjunctival hyperemia
• Mild eye irritation - typically less than trifluridine
• Punctate corneal staining - uncommon
• Allergic blepharoconjunctivitis - uncommon

Systemic

• Negligible - minimal systemic absorption from topical gel

Ganciclovir Gel vs. Trifluridine

For many patients, ganciclovir gel is preferred because of more convenient dosing and less corneal toxicity. Trifluridine retains activity against thymidine-kinase-deficient HSV, which is uncommon in immunocompetent patients but more frequent in immunocompromised hosts.

Adjunctive Therapy

Mechanical Debridement

For dendritic ulcers, gentle debridement of loose epithelium with a sterile cotton swab is sometimes performed in addition to antiviral therapy.

Oral Antivirals

Valacyclovir, acyclovir, or famciclovir are added for stromal disease, recurrent disease, or as prophylaxis. The HEDS trials established the value of oral antivirals in many forms of HSV eye disease.

Topical Steroids

• Avoided in active epithelial disease
• Used carefully in stromal keratitis under supervision, often combined with oral antiviral coverage

Frequently Asked Questions

Why do many clinicians prefer ganciclovir gel over trifluridine?

Two reasons: dosing is far more convenient (5 times daily vs 9), and corneal tolerance is better. The trade-off is that ganciclovir is susceptible to thymidine-kinase-deficient HSV strains, while trifluridine is effective against them. In typical first episodes of HSV keratitis, ganciclovir gel is commonly preferred where available and tolerated.

Is the gel as effective as the trifluridine drops?

Head-to-head studies have shown ganciclovir gel is comparable in efficacy to trifluridine for typical epithelial HSV keratitis, with similar resolution rates and times to healing.

Why does my vision blur after putting in the gel?

The gel temporarily forms a film over the cornea that smooths out and clears within minutes to half an hour. This brief blurring is expected and is not a side effect to worry about. Many patients dose the gel before periods of less critical visual demand.

Can I wear contact lenses during treatment?

No. Active herpes keratitis is a contraindication to contact lens wear. Resume contact lens use only after full healing and clearance from your doctor.

What happens if my ulcer does not heal in 10 days?

The doctor will reassess. Sometimes the agent is switched (often to trifluridine), sometimes oral antivirals are added, sometimes the diagnosis is reconsidered. Persistent dendritic ulcers may indicate resistance, atypical HSV, or another diagnosis.

Is this the same as systemic ganciclovir for cytomegalovirus?

Same active molecule, different application. IV ganciclovir or oral valganciclovir (the prodrug converted to ganciclovir in the body) is used systemically for cytomegalovirus disease in immunocompromised patients. Ganciclovir gel is a topical formulation used only for ocular HSV at much lower total exposure.