Pharmacokinetic and Pharmacodynamic Assessment of Valganciclovir in Infants With Congenital Cytomegalovirus Infection

Valganciclovir (VGCV) is administered at a dose of 16 mg/kg 2 times daily for 6 months to treat symptomatic congenital cytomegalovirus (CMV) infections. During the treatment period, approximately 20% of the patients developed grade 3 or higher neutropenia. Currently, information on the pharmacokinetics and pharmacodynamics of ganciclovir, an active metabolite of VGCV, in infants is limited. In the current study, the relationship between ganciclovir concentration and neutropenia was investigated, and a population pharmacokinetic (PPK) model of ganciclovir in infants with symptomatic congenital CMV infection was developed. Japanese infants who were prescribed oral VGCV for symptomatic congenital CMV infections between July 2017 and January 2021 were included. The relationship between the observed trough ganciclovir concentrations and neutrophil counts was examined. PPK analysis was performed to evaluate the covariates affecting the pharmacokinetics of ganciclovir. Twenty-seven ganciclovir serum samples from 8 patients were analyzed. A moderate negative correlation was observed between the observed trough ganciclovir concentration and neutrophil count. PPK model analysis showed that postmenstrual age (PMA) affected the total body clearance of ganciclovir after correcting for the empirical allometric scaling of body weight. Based on PMA and body weight, a nomogram to achieve the target area under the concentration-time curve from 0 to 24 hours of 40-60 mcg·h·mL-1 of ganciclovir was calculated. The relationship between neutrophil count and ganciclovir trough concentration in infants was clarified. The PPK model showed that the dose of VGCV should be reduced in patients with a low PMA to achieve target exposure.