ABSTRACT
PURPOSE: Cyclosporine is a potent immunosuppressive drug used in organ transplantation. Because of its substantial toxic effect, narrow therapeutic index, and the inter-individual variability of pharmacokinetics, therapeutic drug monitoring of the whole blood cyclosporine concentration has been recommended. We have investigated the comparability of the results of two immunoassay systems, the affinity column- mediated immunoassay (ACMIA) and the microparticle enzyme immunoassay (MEIA), and compared the differences in the cyclosporine concentrations between the two methods in relation to the hematologic and biochemical values. METHODS: One hundred twenty-one blood samples from kidney recipients were used. We used Dimension? RxL HM with a CSA Flex? reagent cartilage for the ACMIA method and AXSYM? Cyclosporine for the MEIA method. RESULTS: Cyclosporine concentrations measured by the ACMIA method (n=121) were closely correlated with those measured by the MEIA method (r=0.948, P<0.0001). The Bland-Altman plot using concentration differences between the two methods and the average of the two methods also showed no specific trends (R2=0.02, P=0.125). Except hematocrit, other hematologic and biochemical value (albumin, total bilirubin) didn't affect to both cyclosporine level by MEIA and ACMIC method. Both cyclosporine levels determined by the MEIA method and the ACMIA method were positively correlated with hematocrit (P<0.05). CONCLUSION: The ACMIA method used for a cyclosporine assay is precise and has advantages, including the lack of a required pretreatment procedure, and shows same influence by hematocrit compared with the MEIA.