Valaciclovir (also spelled Valacyclovir) is an oral antiviral prodrug of acyclovir, used to treat herpes virus infections. After oral administration, valaciclovir is rapidly converted to acyclovir in the body by intestinal and hepatic esterases. Acyclovir inhibits viral DNA polymerase, blocking viral replication. Valaciclovir offers improved bioavailability compared to acyclovir, allowing for less frequent dosing.
Indications include:
∙ Herpes zoster (shingles)
∙ Genital herpes (initial and recurrent episodes)
∙ Cold sores (herpes labialis)
∙ Suppression of recurrent genital herpes
∙ Cytomegalovirus (CMV) prophylaxis in transplant patients
Parent: Valaciclovir
Parent: Valaciclovir
Parent: Valaciclovir
Parent: Valaciclovir
Parent: Valaciclovir
Parent: Valaciclovir
Parent: Valaciclovir
Parent: Valaciclovir
Parent: Valganciclovir/Ganciclovir
Impurities in valaciclovir can result from its semi-synthetic synthesis from acyclovir, particularly during esterification with L-valine, and from degradation due to hydrolysis or oxidation. Due to its chronic or recurrent use, impurities must be tightly controlled in compliance with ICH Q3A/B and USP/EP monographs.
Process-Related Impurities
Degradation Impurities
Elemental Impurities
Analytical Techniques for Impurity Detection
UV-Vis Spectroscopy – for monitoring degradation and content uniformity
Valaciclovir is used to treat and suppress herpes virus infections, including shingles, genital herpes, cold sores, and CMV prophylaxis in immunocompromised patients.
It is a prodrug of acyclovir, which gets converted in the body and inhibits viral DNA polymerase, preventing the replication of herpesviruses.
Yes, valaciclovir offers better oral bioavailability, allowing for fewer daily doses, which improves patient compliance.
It is generally stable but can hydrolyze into acyclovir and valine under humid or acidic conditions. It should be stored in cool, dry, and airtight packaging, protected from moisture and light.
