Products
Zovirax ophthalmic ointment (30 mg/g) is no longer marketed in many countries as of 2019. In 2020, Xorox ophthalmic ointment (also 30 mg/g) was approved.
Structure and properties
Aciclovir (C8H11N5O3, Mr = 225.2 g/mol) exists as a white crystalline powder that is sparingly soluble in water. It is the prodrug of the active aciclovir triphosphate. Aciclovir is an analog of the nucleoside deoxyguanosine – hence the active ingredient name. The suffix -vir refers to virus.
Effect
Aciclovir (ATC J05AB01) has antiviral properties against herpes simplex virus types 1 and 2 (HSV-1, HSV-2) and against varicella zoster virus (VZV). It is a prodrug that is converted to aciclovir triphosphate in virus-infected cells by viral thymidine kinase and subsequently by cellular kinases. Aciclovir triphosphate is used by viral polymerase as a false substrate in DNA synthesis. This leads to chain termination in nucleic acid formation and inhibition of viral replication. Because the viral enzyme is involved in activation, aciclovir has high selectivity for infected cells.
Indications
For the treatment of herpes infections of the eye, particularly herpes simplex keratitis.
Dosage
According to the SmPC. The ophthalmic ointment is applied to the lower conjunctival sac five times daily at approximately 4-hour intervals. Treatment should be continued for up to three days after healing.
Contraindications
- Hypersensitivity
For complete precautions, see the drug label.
Interactions
There are no known interactions when used topically.
Adverse effects
The most common potential adverse effects include local reactions to the eye such as superficial punctate keratopathy, transient mild burning and blurred vision after application, and conjunctivitis.
