Genclovir

Indications

Ganciclovir is an antiviral medicine. As a 0.15% eye gel it is used to treat acute herpes simplex keratitis, a viral infection of the clear front surface of the eye (cornea) that causes dendritic ulcers. As an intravenous infusion in hospital it is used to treat and prevent serious cytomegalovirus (CMV) infections in people with weak immunity, such as after transplants or with advanced HIV.

How It Works

Inside cells infected with herpes viruses, Ganciclovir is converted into an active form that blocks the viral DNA polymerase, the enzyme the virus needs to copy itself. This stops the virus from multiplying, allowing the body's defences and the eye surface to heal.

Dosage and Administration

Eye gel (adults): usually 1 drop in the lower eyelid pocket of the affected eye 5 times a day until the corneal ulcer has healed, then 3 times a day for a further 7 days, or as directed by your eye doctor. Treatment usually does not go beyond 21 days. Wash hands before and after use and do not touch the tip to the eye. Remove contact lenses during treatment. The intravenous form is given only by a doctor or nurse in hospital, with the dose set by body weight and kidney function.

Interactions

• Eye gel: very little reaches the blood, so interactions are unlikely; leave at least 5 minutes between different eye medicines.
• Intravenous form: Zidovudine, Mycophenolate, cancer medicines and other drugs that lower blood counts increase the risk of blood problems; Imipenem with Cilastatin may increase the risk of fits; Probenecid raises its levels.

Contraindications

• Allergy to Ganciclovir or Valganciclovir, or to Aciclovir or Valaciclovir.
• For the intravenous form: very low white cell or platelet counts.

Side Effects

The eye gel may cause brief blurred vision, stinging, burning or irritation of the eye, and small spots on the cornea. The intravenous form can lower white cells, red cells and platelets, and cause fever, diarrhoea, nausea and kidney changes.

Get urgent medical help if eye pain or vision gets worse, if there is no improvement after a few days, or, with the intravenous form, if you develop fever, sore throat, unusual bleeding or bruising, or swelling of the face or throat.

Pregnancy and Lactation

Intravenous Ganciclovir may harm an unborn baby and affect fertility; effective contraception is needed during and after treatment as directed by the doctor, and breastfeeding should be stopped. With the eye gel, absorption is very low, but use in pregnancy and breastfeeding only if your doctor advises it.

Precautions and Warnings

• Do not drive until blurred vision after applying the gel has cleared.
• Do not share the eye gel with others.
• Intravenous treatment needs regular blood count and kidney tests.

Overdose

Extra eye gel is not expected to be harmful; rinse the eye with clean water if irritated. Intravenous overdose can seriously lower blood counts and affect the kidneys and is managed in hospital; dialysis can remove it.

Therapeutic Class

Antiviral (nucleoside analogue).

Storage

Store below 30°C in a dry place, away from light and out of the reach of children. Do not freeze. Discard the eye gel 4 weeks after opening. Intravenous vials are stored as directed on the pack.