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Clinical Pharmacology Unit (UPC)

Pharmacokinetics of Oral Valganciclovir in the Transplanted Child

Study Design

Cytomegalovirus infection (CMV) is one of the leading causes of morbidity and mortality in transplant patients. The impact of a CMV infection in grafted patients is two-fold: it causes indirect damage such as organ rejection (solid organ transplant) or graft rejection (hematopoietic stem cells), and may also evolve into an invasive CMV disease with a dreadful prognosis. In order to prevent these complications, the clinical practice adopted for these patients rests on preemptive actions: administration of a specific antiviral treatment (ganciclovir - GCV) immediately upon detection of a viremia (asymptomatic infection) through a highly sensitive gene amplification method (Polymerase Chain Reaction - PR). The GCV is then administered intravenously (IV) until 2 consecutive negative tests are obtained (4 to 6 weeks following treatment, on average). Whereas an oral prodrug of GCV, valganciclovir (VGC), has become the first instance treatment for adults in this clinical situation, the absence of pharmacokinetic data prevents us from using this drug on children.


We hypothesize that the pharmacokinetics of oral VGC in children differs from those described in adults. Thus, extrapolating accepted adult doses to children is possibly inappropriate.

Main Objective

We are attempting to determine the pharmacokinetics of oral VGC in pediatric transplant recipients. Moreover, being able to dose oral VGC blood concentrations will: (i) allow clinicians to benefit from a real-time therapeutic follow-up; (ii) enable us to demonstrate the importance of monitoring this drug in children; and (iii) substitute an oral therapeutic mode with an IV treatment for our patients.

Patients and Methods

Transplant patients are monitored weekly for CMV viral load (quantitative PCR method) in the first 100 days post-transplant. A positive test automatically leads to a treatment of antiviral IV GCV until the patient has two consecutive negative tests. During this period, in which the viral load is undetectable, the administered IV treatment will be replaced by oral VGC. This IV-oral substitution will take place under a double control of blood concentration GCV/VGC dosage and viral load quantification, thus ensuring therapeutic efficacy at a time in the treatment when viral replication is nil. Two pharmacokinetic studies will be conducted, one under IV GCV and the other under oral VGC, allowing for a comparison of pharmacokinetic parameters not only with those reported in adults but also those observed in patients receiving the IV treatment.

Blood samples will be drawn by central catheter and will measure GCV and VGC blood concentrations, both prior to administration of the drug and at various subsequent times. The analysis will be done by high-performance liquid chromatography with detection through diode array and mass spectrometry at the Clinical Pharmacology Unit Laboratory of the CHU Sainte-Justine. The results, given in real time, will enable the calculation of multiple pharmacokinetic variables and could lead to a dose adjustment, if needed.


Access to the possibility of a real-time dosage by HPLC of GCV and VGC will have many effects: (i) The patient will benefit from an “alleviated” therapeutic regimen, since oral medication will be used, thus limiting the use of the central catheter (PICC line), in turn reducing the risk of nosocomial infections; (ii) The clinician will adapt the oral VGC posology as needed to fit the therapeutic window, which is possibly similar to the one observed in IV administration; (iii) It will be possible for the institution to modify its clinical and therapeutic approach by allowing a change from an IV treatment to an oral treatment, which will reduce the length of hospitalization, risk of nosocomial infections, and, as a result, health costs.


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Updated on 10/14/2014
Created on 10/14/2014
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