What is the recommended dosage of valgancyclovir (Valcyte) for pediatric patients with cytomegalovirus (CMV) positive?

Valganciclovir Dosing for Pediatric Patients with CMV Infection

The recommended dosage of valganciclovir for pediatric patients with CMV infection is calculated using the formula: Dose (mg) = 7 × BSA × CrCl, where BSA is body surface area and CrCl is creatinine clearance calculated using the modified Schwartz formula. 1

Dosing Formula and Calculation

The FDA-approved dosing algorithm for valganciclovir in pediatric patients accounts for both body size and renal function:

• Formula: Pediatric Dose (mg) = 7 × BSA × CrCl
• BSA calculation: Mosteller formula = √(Height (cm) × Weight (kg) / 3600)
• CrCl calculation: Modified Schwartz formula = k × Height (cm) / Serum Creatinine (mg/dL)

Age-specific k values for Schwartz formula:

• 0.33: Infants <1 year with low birth weight for gestational age
• 0.45: Infants <1 year with appropriate birth weight for gestational age
• 0.45: Children 1 to <2 years
• 0.55: Boys 2 to <13 years and girls 2 to <16 years
• 0.70: Boys 13 to 16 years

Important Dosing Considerations

• If calculated Schwartz CrCl exceeds 150 mL/min/1.73m², use 150 mL/min/1.73m² as the maximum value 1
• Round all calculated doses to the nearest 10 mg increment
• Maximum dose should not exceed 900 mg
• Valganciclovir should be taken with food to increase bioavailability 1

Treatment Duration

For CMV prophylaxis in pediatric heart transplant patients (4 months to 16 years):

• Start within 10 days of transplantation
• Continue until 100 days post-transplantation 1

Formulation Selection

• Valganciclovir oral solution is preferred for pediatric patients as it allows for more precise dosing
• Tablets (450 mg) may be used if the calculated dose is within 10% of the tablet strength (405-495 mg)
• Assess the child's ability to swallow tablets before prescribing 1

Monitoring Requirements

• Regular monitoring of serum creatinine levels
• Complete blood counts with differential to monitor for hematologic toxicity
• CMV viral load monitoring to assess treatment efficacy 2

Adverse Effects to Monitor

• Neutropenia: Most frequent toxicity, may require dose reduction or interruption
• Anemia and thrombocytopenia: Monitor complete blood count
• Renal toxicity: Monitor serum creatinine
• Other potential effects: CNS effects, gastrointestinal dysfunction, elevated liver enzymes 3

Dosage Adjustment for Renal Impairment

Adjust dose according to creatinine clearance:

• CrCl ≥60 mL/min: No adjustment needed
• CrCl 40-59 mL/min: 50% of calculated dose
• CrCl 25-39 mL/min: 50% of calculated dose once daily
• CrCl 10-24 mL/min: 50% of calculated dose every 2 days
• CrCl <10 mL/min: Not recommended 2, 1

Alternative Dosing Approaches

While the BSA and CrCl-based formula is FDA-approved, some centers use alternative weight-based dosing:

• 17 mg/kg/day has shown satisfactory efficacy with potentially fewer adverse effects 4, 5
• This approach may result in lower ganciclovir exposure, especially in young children with low BSA 5

The FDA-approved BSA and CrCl-based formula provides consistent ganciclovir exposure across different age groups and organ recipient types, making it the preferred approach for most pediatric patients with CMV infection.