What is Acyclovir?

Acyclovir is a synthetic nucleoside analogue with antiviral activity against herpes simplex virus types 1 and 2 (HSV-1, HSV-2) and varicella-zoster virus (VZV). It was one of the first antiviral agents to be developed and remains a mainstay in the treatment of herpesvirus infections. The drug is selectively activated by viral thymidine kinase, making it highly specific for virus-infected cells.

Indications

Acyclovir is indicated for the treatment of initial and recurrent genital herpes, herpes labialis (cold sores), herpes zoster (shingles), varicella (chickenpox), and herpes simplex encephalitis. It is also used for prophylaxis of herpes simplex infections in immunocompromised patients.

Dosage

For genital herpes (initial): 200 mg five times daily for 10 days. For herpes zoster: 800 mg five times daily for 7-10 days. For varicella: 800 mg four times daily for 5 days. IV acyclovir is used for severe infections at 5-10 mg/kg every 8 hours. Adequate hydration is essential during treatment.

Side Effects

Common side effects of oral acyclovir include nausea, diarrhea, and headache. IV administration may cause phlebitis at the injection site and, rarely, renal impairment due to crystallization in the renal tubules. Adequate hydration and slow infusion rates help minimize renal toxicity.