Valacyclovir Hydrochloride is an antiviral drug used primarily to treat infections caused by herpes viruses, including genital herpes, cold sores, and shingles.
Mechanism of Action: - Conversion to Acyclovir: Valacyclovir is a prodrug, meaning it is converted in the body to the active antiviral agent acyclovir. This conversion occurs primarily in the liver and the intestinal wall.
Inhibition of Viral DNA Synthesis: Acyclovir triphosphate, the active form of acyclovir, inhibits viral DNA synthesis. It competes with deoxyguanosine triphosphate (dGTP) for incorporation into viral DNA during replication. Once incorporated, it acts as a chain terminator, preventing further viral DNA synthesis and halting viral replication.
Selective Action: The phosphorylation (activation) of acyclovir to its triphosphate form is facilitated by the viral enzyme thymidine kinase (especially in HSV and VZV), making it highly selective for virus-infected cells. This minimizes damage to uninfected cells, reducing side effects.
