Acyclovir is an antiviral agent which is highly active in vitro against Herpes simplex (HSV) types I and II and Varicella zoster viruses, but its toxicity to mammalian cells is low. Acyclovir is phosphorylated to the active compound Acyclovir triphosphate after entry into herpes infected cell. The ­first step in this process requires the presence of the viral-coded thymidine kinase. Acyclovir triphosphate acts as an inhibitor of and substrate for the herpes specifi­ed DNA polymerase preventing further viral DNA synthesis without affecting normal cellular processes.

Acyclovir is indicated for the treatment of Herpes simplex keratitis.

The dosage for all age groups is the same. A 10 mm ribbon of the ointment should be placed inside the lower conjunctival sac ­five times a day at approximately four hourly intervals. Treatment should continue for at least 3 days after healing

Acyclovir is contraindicated in patients known to be hypersensitive to Acyclovir or Valacyclovir

Very common: Superfi­cial punctate keratopathy. This did not necessitate an early termination of therapy and healed without apparent sequelae. Common: Transient mild stinging of the eye occurring immediately following application, conjunctivitis. Rare: Blepharitis.

Overdose Effects

No adverse effects would be expected if the entire contents of the tube containing 90 mg Acyclovir were ingested orally.

Pregnancy & Lactation

Pregnancy category B. There are no adequate and well-controlled studies of Acyclovir in pregnant women. It is not known whether topically applied Acyclovir is excreted in breast milk.

Precautions & Warnings

The recommended dosage, frequency of applications, and length of treatment should not be exceeded.