💡💊Acyclovir is a prodrug that is phosphorylated by viral thymidine kinase into its active form, acyclovir triphosphate. This active form inhibits viral DNA polymerase, preventing viral replication. ☀️Nephrotoxicity (Crystalline nephropathy—hydrate well!). ☀️Probenecid & Cimetidine → Increase acyclovir levels. ☀️Dose adjustment required in renal impairment. ☀️Early initiation (within 72 hours) improves outcomes in VZV infections. ☀️IV formulation preferred for severe cases like encephalitis.