Herpirax (Aciclovir)

Herpirax is indicated for the topical management of herpes simplex virus infections on the skin and mucous membranes. It is commonly employed to reduce the duration and severity of lesions caused by the virus.

• Treatment of oral herpes (cold sores) on the lips and perioral area.
• Management of genital herpes lesions on external genital skin.
• Relief of recurrent herpes simplex outbreaks on the face or neck.
• Prophylactic use in individuals with frequent recurrences to lessen lesion development.
• Adjunct therapy for herpes simplex infections in immunocompromised patients under medical supervision.

• Aciclovir is a nucleoside analogue that is selectively phosphorylated by viral thymidine kinase to aciclovir monophosphate, then further converted by cellular kinases to the active triphosphate form. The triphosphate competitively inhibits viral DNA polymerase, leading to premature chain termination during viral DNA synthesis, thereby suppressing replication of herpes simplex virus in infected cells.

Adverse reactions to topical aciclovir are generally mild but can vary in frequency and severity.

Common

• Local skin irritation or burning sensation at the application site.
• Redness or erythema surrounding the treated area.
• Itching or mild pruritus.
• Dryness or peeling of the skin.
• Minor swelling or edema.

Serious

• Allergic contact dermatitis presenting with extensive rash, blistering, or hives.
• Severe skin ulceration or necrosis at the site of application.
• Systemic hypersensitivity reactions such as angioedema or anaphylaxis (rare).

When using Herpirax, certain safety considerations should be observed to minimize risks.

• Avoid applying to broken skin, open wounds, or mucous membranes unless directed by a healthcare professional.
• Discontinue use and seek medical advice if signs of an allergic reaction develop.
• Use with caution in patients with known hypersensitivity to aciclovir or related antiviral agents.
• Pregnant or breastfeeding individuals should consult a clinician before use, as safety data are limited.
• Keep the product out of reach of children and store at room temperature away from direct sunlight.
• Do not use concurrently with other topical antiviral preparations without professional guidance.

Topical aciclovir has limited systemic absorption, but certain interactions may still be relevant.

Avoid

• Concurrent use of other topical agents containing irritants (e.g., salicylic acid) that could increase skin irritation.
• Application over areas treated with other prescription antivirals without medical advice.

Use with caution

• Systemic antiviral therapy (e.g., oral aciclovir) as overlapping mechanisms may increase local drug concentration.
• Topical corticosteroids, which may mask irritation signs.
• Products containing alcohol or strong fragrances that could exacerbate dryness or irritation.
• Use on extensive body surface areas in patients with renal impairment, as systemic absorption may be higher.