We studied the disposition of cyclosporine (CyA) in 8 living related donor partial liver transplant recipients (patient A-H). CyA blood levels were determined by fluorescence polarization immunoassay with specific monoclonal antibody (m-FPIA) and fluorescence polarization immunoassay with non-specific polyclonal antibody (p-FPIA). The ratio of the blood levels of CyA determined by p-FPIA to those by m-FPIA varied significantly, because the levels determined by p-FPIA were influenced by the function of graft liver. Thus, the levels of CyA determined by p-FPIA could not be used for the adjustment of CyA dose. The CyA dose ratios [DR ; CyA blood level (mg/l)/dose (mg/kg)] of 3 in 8 patients were relatively large in 1-4 d after the transplant operation, however, it decreased within 2-5 d after the operation. CyA DR gradually increased from 5-8 d after the transplantation, and it reached to a maximum in 10-13 d in 5 patients to whom CyA was administered intravenously over 12 d after transplantation. The average ratio of DR in oral administration to that in intravenous one was about 43%. CyA bioavailability in the patient of living related partial liver transplantation was as usual as that in other organ transplant patient except for cadaveric liver transplant patients. The average DR of intravenous CyA administration in liver transplant recipients was 1.5 times larger than that in bone marrow transplant patients. CyA disposition had large inter-individual and intra-individual variation, and CyA blood level and DR varied in clinical time course at least within 1.5 month after operation. Therefore, it is necessary to measure CyA blood level frequently and to adjust CyA dose.
