Acyclovir cream is a herpes simplex virus (HSV) nucleoside analogue DNA polymerase inhibitor indicated for the treatment of recurrent herpes labialis (cold sores) in immunocompetent adults and adolescents aged 12 years and above.

Acyclovir is an antiviral agent effective against herpes simplex virus. It is a synthetic purine nucleoside analogue that exhibits inhibitory activity in both cell culture and in vivo against HSV type 1 (HSV-1) and type 2 (HSV-2). The antiviral activity of acyclovir is highly selective due to its strong affinity for the viral enzyme thymidine kinase (TK). This enzyme converts acyclovir into acyclovir monophosphate, which is subsequently converted into diphosphate by cellular guanylate kinase and then into triphosphate by other cellular enzymes. Acyclovir triphosphate inhibits viral DNA replication in three ways: By competitively inhibiting viral DNA polymerase By incorporation into the viral DNA chain, causing chain termination By inactivating viral DNA polymerase

Acyclovir cream should be applied five times per day for four days. Therapy should be initiated as early as possible following the onset of signs or symptoms of herpes labialis i.e., during the prodrome or when lesions appear. For adolescents 12 years of age and older, the dosage is the same as in adults.

Clinical data have shown no significant interactions when Acyclovir cream is used alongside other topical or systemic medications. Due to its minimal systemic absorption, clinically relevant drug interactions are unlikely.

Acyclovir cream is contraindicated in patients with known hypersensitivity to acyclovir, valacyclovir, or any of the components of the formulation.

The most commonly reported adverse reactions at the application site include dry lips, skin peeling (desquamation), dry skin, cracked lips, burning sensation, itching (pruritus), skin flaking, and stinging sensation. Each of these reactions occurred in less than 1% of patients using Acyclovir cream or placebo. A small number of patients discontinued treatment due to adverse events.

Pregnancy Category B: There are no well-controlled studies of Acyclovir cream in pregnant women. It should be used during pregnancy only if the expected benefit outweighs the potential risk to the fetus. It is unknown whether topically applied acyclovir is excreted in human breast milk; however, systemic exposure after topical use is minimal.

Acyclovir cream should be applied only to the affected external areas of the lips and face in patients with herpes labialis. It is not recommended for use on mucous membranes due to lack of data. The cream is intended for external (cutaneous) use only and should not be applied to the eyes, inside the mouth, or inside the nose. It may cause local irritation or contact reactions. Its effectiveness in immunocompromised patients has not been established.

Pediatric Use: An open-label, uncontrolled study of Acyclovir cream 5% was conducted in patients aged 12 to 17 years with recurrent herpes labialis, using the same dosing regimen as adults. The safety profile was similar to that observed in adults. Safety and effectiveness in children below 12 years of age have not been established.

Geriatric Use: Clinical trials of Acyclovir cream did not include sufficient patients aged 65 years and above to determine differences in response compared to younger individuals. However, available clinical experience does not indicate any significant difference between elderly and younger patients. Systemic absorption following topical application remains minimal.

Topical antiviral agents

Store Acyclovir cream at room temperature between 20°C and 25°C.