The need for area under the curve measurements in the field of ganciclovir therapeutic drug monitoring in children: a case report

BACKGROUND: Ganciclovir pharmacokinetics is characterized by a high variability in drug exposure. Usually, monitoring of ganciclovir exposure is performed by measuring trough concentration. However, due to the specificity of pediatric pharmacokinetics, trough concentration measurements may not be a relevant surrogate of ganciclovir exposure. Area under the curve of concentration (AUC) may be a more appropriate biomarker. CASE PRESENTATION: We report the case of 3.6-year-old boy with Emberger syndrome with a cytomegalovirus reactivation occurring after allogenic hematopoietic stem cell transplantation. After a few days of treatment with intravenous ganciclovir, sub-therapeutic trough ganciclovir concentrations were measured (< 0.5 µg/mL) and viral load still increased. Ganciclovir dosage was increased by two-fold to deal with this treatment failure. Trough concentrations remained sub-therapeutic. The patient had hematologic disorder therefore it was decided to estimate ganciclovir AUC to assess more accurately drug exposure before any further dosage modification. AUC(0–12 h) was measured at 51 μg h/mL, which was within the therapeutic range (40–60 μg h/mL). Afterward, viral load decreased and became undetectable. CONCLUSIONS: This case report highlights that monitoring ganciclovir exposure based on AUC should be performed to tailor drug dosage in order to improve treatment efficacy and safety in pediatric patients.