1990 年 21 巻 2 号 p. 369-376
The fluorescence polarization immunoassay (FPIA) method for determination of cyclosporin in whole blood was evaluated and compared with the high-performance liquid chromatography (HPLC) and the radioimmunoassay (polyclonal-RIA) methods. The coefficients of variation for the within-run and between-run precisions were 5% and 7%, respectively, for samples ranging in concentration from 350 to 1, 750 ng/ml. Recoveries were determined by adding cyclosporin at concentrations from 250 to 1, 750ng/ml to patient whole blood ; they were, on the average, 98.1%. The calibration curve was stable throughout a 10-week study period. There was no clinically significant interference for the FPIA assay due to icterus, lipemia, or other commonly used drugs. There was considerable variation of the ratio of the FPIA result to the HPLC result, whereas there was a good correlation between the FPIA and the polyclonal-RIA results (Y=0.9X-27.2, r=0.983, n=45, P<0.005), when evaluated using specimens from renal transplant patients receiving cyclosporin orally. In clinical practice, although higher blood levels of cyclosporin by the FPIA do not always correspond to more abnormal results in the clinical laboratory tests, an elevation of the trough level by the FPIA should be useful as an indicator of the risk of occurrence of tissue toxicity. It was concluded that the FPIA assay for cyclosporin in whole blood showed sufficient reproducibility and reliability to be used for either emergency or routine analysis in clinical practice, and serves as a practical alternative to the polyclonal-RIA.
