Overview
Valganciclovir is an antiviral prodrug converted to ganciclovir, used primarily for prevention and treatment of cytomegalovirus (CMV) infections in immunocompromised patients, particularly transplant recipients and those with AIDS. It works by inhibiting viral DNA replication and is administered orally with dosage adjustments based on renal function.
Mechanism of Action
Valganciclovir is a prodrug that is rapidly converted to ganciclovir in the body. Ganciclovir is phosphorylated by viral and cellular kinases to form ganciclovir triphosphate, which competitively inhibits viral DNA polymerase and incorporates into viral DNA, causing chain termination and inhibition of CMV replication.
Indications
- Prevention of CMV disease in kidney, heart, and kidney-pancreas transplant recipients at high risk
- Treatment of CMV retinitis in patients with AIDS
- Prevention of CMV disease in pediatric solid organ transplant recipients
Common Doses
- 450 mg tablets
- 900 mg tablets
Dosage
For CMV prevention in adult transplant patients: 900 mg once daily starting within 10 days of transplantation until 100 days post-transplant. For CMV retinitis: 900 mg twice daily for 21 days induction, then 900 mg once daily maintenance. All doses require adjustment based on renal function.
Contraindications
- Hypersensitivity to valganciclovir, ganciclovir, or any component of the formulation
Side Effects
- Diarrhea
- Pyrexia
- Fatigue
- Nausea
- Tremor
- Neutropenia
- Anemia
- Leukopenia
- Thrombocytopenia
- Headache
- Insomnia
- Urinary tract infection
- Vomiting
- Upper respiratory tract infection
Interactions
- Imipenem-cilastatin: Contraindicated due to seizure risk
- Cyclosporine/amphotericin B: Monitor renal function
- Mycophenolate mofetil: Monitor for hematological and renal toxicity
- Other myelosuppressive/nephrotoxic drugs: Increased toxicity risk
- Didanosine: Monitor for pancreatitis
- Probenecid: Increases ganciclovir levels; may need dose reduction
Counseling Points
- Take with food to improve absorption
- Complete full course as prescribed
- Report signs of infection, unusual bleeding, or bruising immediately
- Use effective contraception during treatment and for 30 days after
- Maintain adequate hydration
- Regular blood tests are required to monitor for toxicity
- Do not crush or break tablets