Pharmacokinetics of Mmf and Valganciclovir

Overview

The primary objective of this study is to determine whether a clinically significant PK drug interaction ( a 30% difference in the AUC of MPA) exists between mycophenolate mofetil (under steady state conditions) and VGCV in renal and cardiac transplant recipients. This study will provide clinically relevant information to the transplant community. It will more clearly delineate whether a clinically significant PK drug interaction exists between mycophenolate mofetil (under steady-state conditions)and VGCV. Given the established dose/efficacy relationship of both MMF and VGCV, this study will provide improved dosing guidelines and potentially avoid adverse outcomes due to empiric dosage adjustments.

Mycophenolate mofetil (immunosuppressant, MMF) and valganciclovir (antiviral, VGCV) are commonly administered together in transplant patients. Following oral administration, both MMF and VGCV are metabolized to active forms, mycophenolic acid (MPA) and gancoclovir (GCV) respectively. Both MPA and GCV are eliminated through kidney and renal excretion, but there is no data on how MPA pharmacokinetic parameters are affected by GCV at steady state condition. Both MPA and GCV can cause neutropenia and although unsubstantiated, some clinicians have observed an increased occurrence of neutropenia when these agents are used in combination. In the presence of neutropenia, practitioners are often challenged when making decisions regarding whether the dosage of one or both agents should be reduced. It would be useful to know whether the neutropenia is due to increased drug concentration or whether it is due to direct effects of these agents on the bone marrow.