Comparative FK506 Drug Levels of Once Daily Advagraf in First Nations and Caucasian Patients With Liver Transplants

Background: Previous studies have documented differences in the pharmacokinetics (PK) of a once daily FK506 formulation (Advagraf) based on patient ethnicity. These findings may be of particular relevance to the First Nations population who constitute a large and increasing segment of the liver transplant population in Canada. Aim: The purpose of the present study is to determine whether PK differences exist for Advagraf in First Nations compared to Caucasian liver transplant patients. Objectives: 1. Document and compare PK determinations for Advagraf in First Nations and Caucasian patients with stable liver transplants. 2. Document and compare CYP3A gene expression profiles in the two ethnic populations. Study Design: * single-centre, open-label * consecutive enrollment (N=8/group) * self-identified adult First Nations and Caucasian ethnic cohorts * 7 day steady state conversion (mg/mg/day) from twice to once daily FK506 formulation * timed blood samples at 0, 1.5, 2, 4, 6, and 24 hours post medication * PK determinations:concentration at zero time (C0), time to maximum concentration (Tmax),Area Under the Curve (AUC 0-24), apparent oral clearance (CLoral) and maximum concentration (Cmax) Methods: * whole blood FK506 levels will be measured by UPLC tandem mass spectroscopy * CYP3A allele analyses will be performed by Dr. Richard Kim, University of Western Ontario Relevance: The results of this study will serve to determine whether present guidelines for conversion of twice to once daily FK506 formulations need be modified for First Nations liver transplant patients.