BackgroundValganciclovir (Valcyte®) has recently been approved for the prevention of cytomegalovirus (CMV) disease in high-risk (CMV donor positive [D+]/recipient negative [R–]) solid organ transplant (SOT) recipients. Large-scale studies describing the pharmacokinetics of valganciclovir in SOT recipients are  lacking.  A  recent  randomised,  double-blind  study  of  valganciclovir  in 364 D+/R– (intent-to-treat population) SOT recipients provided valuable data on which a population pharmacokinetic analysis was performed.MethodsThe pharmacokinetics of ganciclovir from oral ganciclovir (Cymevene®, 1000mg three times daily) and from valganciclovir (900mg once daily) were described with plasma levels from 240 patients (1181 datapoints describing 449 pharmacokinetic profiles) using nonlinear mixed-effects modelling (NONMEM) software. A two-compartment pharmacokinetic model with separate absorption/metabolism and absorption parameters for valganciclovir and ganciclovir, respectively, was developed.ResultsExposure to ganciclovir from valganciclovir averaged 1.65-fold greater than that from  oral  ganciclovir  (95%  CI  1.58,  1.81);  respective  daily  area under the plasma concentration-time curve values were 46.3 ± 15.2 μg · h/mL and 28.0 ± 10.9 μg · h/mL. The relative systemic exposure of ganciclovir was approximately 8-fold higher from valganciclovir than oral ganciclovir. Exposure to ganciclovir from valganciclovir was similar among liver, heart and kidney transplant recipients (46.0 ± 16.1, 40.2 ± 11.8 and 48.2 ± 14.6 μg · h/ mL, respectively). Adherence to the prescribed dosing regimens, which were reduced for renal impairment, gave consistent exposure to ganciclovir.ConclusionOral valganciclovir produces exposures of ganciclovir exceeding those attained with oral ganciclovir, but in line with those reported after standard intravenous administration of ganciclovir. This indicates that oral valganciclovir is suitable in circumstances requiring prophylactic use of ganciclovir and allows for more convenient management of patients at risk of CMV disease.