What is the mechanism of action of acyclovir?

Acyclovir works by interfering with viral DNA replication, which is central to its effectiveness as an antiviral medication. It is specifically designed to target and inhibit the action of the viral DNA polymerase enzyme responsible for synthesizing viral DNA. Once inside the infected cell, acyclovir is converted into its active form, acyclovir triphosphate, which competes with deoxyguanosine triphosphate for incorporation into the growing viral DNA strand. The incorporation of acyclovir into the viral DNA not only stops the elongation of the DNA chain but also renders the DNA molecule non-functional, effectively halting the replication process of the virus and preventing the spread of the infection.

This mechanism is highly selective for virally infected cells, as human DNA polymerase is less sensitive to acyclovir than the viral polymerase, which minimizes the drug’s impact on normal cell functions. This makes acyclovir a valuable therapeutic option for treating infections caused by certain viruses, particularly herpes simplex virus and varicella-zoster virus.