Antiviral Prodrug: Valganciclovir 450 mg tablets contain valganciclovir hydrochloride, which is an L-valyl ester prodrug of ganciclovir.1
Oral Bioavailability: This prodrug formulation was developed to enhance the oral bioavailability of ganciclovir. After oral administration, valganciclovir is rapidly converted to ganciclovir in the intestinal wall and liver.2
Targeted Activity: Valganciclovir is specifically active against viruses of the herpes family, most notably cytomegalovirus (CMV), and is not a general antiviral.3
Dosage Form: The 450 mg strength is a common dosage for both the initial (induction) and long-term (maintenance) treatment regimens, with the number of tablets per dose varying based on the specific clinical indication and patient’s condition.
Advantages
Improved Bioavailability: The prodrug formulation of valganciclovir provides a more reliable and higher level of ganciclovir in the blood than oral ganciclovir itself, with an absolute bioavailability of approximately 60% when taken with food.4
Effective Oral Treatment: It allows for effective oral treatment of serious CMV infections, avoiding the need for intravenous (IV) administration, which is the only route for ganciclovir with similar efficacy.
Once-Daily Dosing: For maintenance therapy or prophylaxis, the dosing is typically once daily, which improves patient convenience and adherence compared to the more frequent dosing required for other treatments.
Reduced Complications: The effectiveness of valganciclovir in preventing CMV disease in transplant patients can reduce the risk of serious complications, including graft rejection and death.
Uses
CMV Retinitis: The primary licensed indication is for the induction and maintenance treatment of cytomegalovirus (CMV) retinitis in adult patients with acquired immunodeficiency syndrome (AIDS).5
Prevention of CMV Disease in Transplants: It is used for the prevention of CMV disease in adult and pediatric solid organ transplant recipients who are at high risk of developing CMV infection from a CMV-positive donor.6
Pediatric Use: It is specifically indicated for the prevention of CMV disease in pediatric patients from birth to 18 years of age who have received a solid organ transplant from a CMV-positive donor.7
Off-Label Uses: While not officially licensed for all of these, it is also used in other situations where CMV infection poses a threat, such as in other immunocompromised states.8
Nature
Antiviral Prodrug: Valganciclovir is a prodrug, meaning it is an inactive compound that is metabolized into the active drug, ganciclovir, inside the body.9
Mechanism of Action: After being converted to ganciclovir, the drug enters CMV-infected cells.10 Inside these cells, it is phosphorylated by a viral enzyme (UL97 protein kinase) to its active triphosphate form. This active form then competitively inhibits viral DNA polymerase and is incorporated into the viral DNA, which terminates chain elongation and blocks viral replication.11
Selective Inhibition: The drug’s mechanism relies on a viral enzyme, making it highly selective for infected cells and less toxic to uninfected host cells.
Renal Excretion: Ganciclovir, the active drug, is primarily eliminated by renal excretion.12 Therefore, dose adjustments are required for patients with impaired kidney function to prevent toxicity.13
Storage
Controlled Room Temperature: Valganciclovir tablets should be stored at controlled room temperature, typically between 20∘C and 25∘C (68∘F and 77∘F).
Protection: Keep the tablets in their original, tightly closed container, protected from light and moisture.
Administration: The tablets should be swallowed whole and not crushed or broken.14 If a tablet is broken, avoid direct contact with the contents, and if contact occurs with skin or eyes, wash thoroughly.
With Food: Valganciclovir tablets should always be taken with food to maximize absorption and bioavailability.15 The dose should be taken at the same time each day to maintain consistent drug levels.
