AN APPROPRIATE STATISTICAL APPROACH FOR THE COMPARISON OF FPIA TO HPLC FOR DETERMINATION OF CYCLOSPORINE CONCENTRATIONS IN ANIMAL-TISSUES

Monoclonal antibody-mediated fluorescence polarization immunoassay (FP IA) is used with the TDx(R) analyzer to determine cyclosporine (CsA) w hole blood concentrations in the clinical laboratory. In this study we compared FPIA with high performance liquid chromatography (HPLC) for quantitation of CsA in tissue homogenates from rats that had been subj ected to CsA administration. After FPIA analysis of drug-free tissue h omogenates spiked with known amounts of CsA showed no significant matr ix effects, FPIA was used to reevaluate CsA concentrations in homogena tes of 238 heart, kidney, liver, spleen, lung, muscle and intestinal t issues that had previously been analyzed by HPLC. As the results of bo th analytical methods expressed variation in measurement imprecision a s a function of CsA concentration, a rigorous weighted Deming regressi on analysis was deemed most appropriate for comparison of the results of the two methods. This statistical evaluation provided convincing ev idence that FPIA is a suitable substitute for HPLC for analysis of CsA concentrations in rat tissues, as the FPIA produced CsA concentration s that were only marginally different statistically from concentration s produced by HPLC.