What is the mechanism by which Acyclovir is activated in the body?

Acyclovir is an antiviral medication primarily used to treat infections caused by certain types of viruses, particularly herpes simplex virus and varicella zoster virus. In the body, Acyclovir requires enzymatic conversion to become active. The process involves the viral enzyme thymidine kinase, which phosphorylates Acyclovir to form acyclovir monophosphate. This is further converted to the triphosphate form by cellular enzymes, which is the active form that interferes with viral DNA synthesis.

The requirement for enzymatic conversion is crucial as it allows Acyclovir to selectively target infected cells. Only those cells that are infected with the virus contain the necessary viral enzymes, leading to a higher concentration of the active drug in infected tissues while minimizing effects on uninfected cells. This selective activation is part of what makes Acyclovir effective as an antiviral treatment.