Cyclosporine metabolite disposition after oral administration in pretransplant end-stage renal disease patients.

The results of this study have shown large interpatient variability in the disposition of M17 and M1 following a single oral dose of CsA in pretransplant end-stage renal disease patients. The differences in the distribution of M17 and M1 in WB and P at 37 degrees C has particular relevance in the interpretation of CsA therapeutic drug monitoring by nonspecific assays such as the RIA. Additional studies characterizing the disposition of M17 and M1 in WB and P separated at 37 degrees C following chronic CsA therapy will be needed to further understand the role of these metabolites in therapeutic drug monitoring of CsA. New analytical techniques or refinements in the present techniques will be required to identify and separate coeluting substances that are now being recognized with the present techniques.