The Sound of Evolution
Valaciclovir
Mechanism of action:
Valaciclovir is the L-valyl ester prodrug of acyclovir. In the intestine and liver, valaciclovir is hydrolyzed by esterases into acyclovir. Within virus-infected cells, acyclovir is first phosphorylated by viral thymidine kinase into acyclovir monophosphate, then converted by guanylate kinase into the diphosphate form, and finally transformed by various cellular kinases into acyclovir triphosphate. It then competitively inhibits viral DNA polymerase and, after being incorporated into viral DNA, causes termination of viral DNA elongation because it lacks a 3'-OH group.
Reference(s):
1. Beutner KR et al. (1995). Valacyclovir: a review of its antiviral activity, pharmacokinetic properties, and clinical efficacy. Antiviral Res.
2. Asahi T et al. (2009). Valacyclovir neurotoxicity: clinical experience and review of the literature. Eur J Neurol.
3. Perry CM et al. (1996). Valaciclovir. A review of its antiviral activity, pharmacokinetic properties and therapeutic efficacy in herpesvirus infections. Drugs.