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P Pillans - One of the best experts on this subject based on the ideXlab platform.

  • The quantification of sirolimus by high-performance liquid chromatography-tandem mass spectrometry and Microparticle Enzyme Immunoassay in renal transplant recipients
    Clinical Therapeutics, 2020
    Co-Authors: Paul Salm, Paul J Taylor, P Pillans
    Abstract:

    Abstract Background Sirolimus, an immunosuppressive agent, is undergoing clinical trials in the prophylaxis of organ rejection. Objectives The aim of this study was to compare the performance of the semi-automated prototype (mode 1 A) Microparticle Enzyme Immunoassay (MEIA) against a validated high-performance liquid chromatography-mass spectrometry (HPLC-MS) method for measuring sirolimus concentrations. A secondary objective was to identify potential factors that may influence sirolimus measurement. Methods The comparison was based on predose samples (n = 841) from 74 renal transplant patients receiving sirolimus therapy. Samples were collected up to 12 months after transplantation. Results The mean (± SD) overestimation by MEIA was 42.5% ± 16.9%. Several variables were investigated to determine potential contributors to the observed overestimation. Stratification of the data based on the mean sirolimus concentrations determined by both assays yielded no statistically significant differences in bias between concentration subgroups within the clinically relevant range. Multiple linear regression analysis identified HPLC-MS sirolimus concentration ( P = 0.03), hemoglobin concentration ( P P Conclusion The MEIA overestimates sirolimus concentrations in renal transplant patients compared with HPLC-MS. The clinical importance of this observed overestimation requires further investigation.

  • evaluation of Microparticle Enzyme Immunoassay against hplc mass spectrometry for the determination of whole blood tacrolimus in heart and lung transplant recipients
    Clinical Biochemistry, 2000
    Co-Authors: Paul Salm, David M Rutherford, Paul J Taylor, Marion Black, P Pillans
    Abstract:

    Objectives: Tacrolimus is an immunosuppressant drug with a narrow therapeutic window and thus requires therapeutic drug monitoring. This study evaluates the suitability of the second-generation Microparticle Enzyme Immunoassay (MEIA II) against a specific method, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS), for the measurement of tacrolimus in both heart- and lung-transplant groups. A secondary objective was to investigate the effect of tacrolimus concentration on MEIA II measurement.

  • analytical performance of Microparticle Enzyme Immunoassay and hplc tandem mass spectrometry in the determination of sirolimus in whole blood
    Clinical Chemistry, 1999
    Co-Authors: Paul Salm, Paul J Taylor, P Pillans
    Abstract:

    The potent immunosuppressant agent sirolimus (rapamycin; Wyeth-Ayerst) is undergoing clinical trials in solid-organ transplantation (1)(2). Evidence suggests that therapeutic drug monitoring of trough sirolimus concentrations may be beneficial for two fundamental reasons: (a) a strong correlation between the trough concentration and the area under the concentration-time curve has been shown; and (b) a strong correlation between the evidence of toxicity and trough concentrations substantially >15 μg/L has been reported (3). To date, there have been only HPLC methods available to measure sirolimus in human whole blood. These include HPLC with mass spectrometric detection (4)(5) and HPLC with ultraviolet detection (6)(7)(8)(9). As an alternative, a semiautomated method utilizing the IMx analyzer (Abbott Diagnostics) that incorporates Microparticle Enzyme Immunoassay (MEIA) technology has been developed. There are two versions of the MEIA for sirolimus in whole blood, the prototype version (Mode 1A) and the recently manufactured premarket version (Mode 1C). Both of these assays are undergoing evaluation based on their analytical performance and clinical use. This study compares the analytical performance of the prototype MEIA (Mode 1A) with HPLC-tandem mass spectrometry (HPLC-MS) within one center through evaluation of interference with endogenous and exogenous compounds, imprecision, recovery, and the quantification range. In addition, blood samples from renal transplant patients receiving sirolimus therapy are compared using both methods. Throughout this study, HPLC-MS was performed as per our reported method (4) and MEIA according to manufacturer’s instructions. All patient specimens were stored at −75 °C until analysis. Investigation into potential interferences in HPLC-MS and MEIA in relation to endogenous compounds was determined based on 209 samples collected into EDTA tubes from 23 renal transplant recipients …

Paul J Taylor - One of the best experts on this subject based on the ideXlab platform.

  • The quantification of sirolimus by high-performance liquid chromatography-tandem mass spectrometry and Microparticle Enzyme Immunoassay in renal transplant recipients
    Clinical Therapeutics, 2020
    Co-Authors: Paul Salm, Paul J Taylor, P Pillans
    Abstract:

    Abstract Background Sirolimus, an immunosuppressive agent, is undergoing clinical trials in the prophylaxis of organ rejection. Objectives The aim of this study was to compare the performance of the semi-automated prototype (mode 1 A) Microparticle Enzyme Immunoassay (MEIA) against a validated high-performance liquid chromatography-mass spectrometry (HPLC-MS) method for measuring sirolimus concentrations. A secondary objective was to identify potential factors that may influence sirolimus measurement. Methods The comparison was based on predose samples (n = 841) from 74 renal transplant patients receiving sirolimus therapy. Samples were collected up to 12 months after transplantation. Results The mean (± SD) overestimation by MEIA was 42.5% ± 16.9%. Several variables were investigated to determine potential contributors to the observed overestimation. Stratification of the data based on the mean sirolimus concentrations determined by both assays yielded no statistically significant differences in bias between concentration subgroups within the clinically relevant range. Multiple linear regression analysis identified HPLC-MS sirolimus concentration ( P = 0.03), hemoglobin concentration ( P P Conclusion The MEIA overestimates sirolimus concentrations in renal transplant patients compared with HPLC-MS. The clinical importance of this observed overestimation requires further investigation.

  • Cloned Enzyme Donor Immunoassay Tacrolimus Assay Compared With High-Performance Liquid Chromatography-Tandem Mass Spectrometry and Microparticle Enzyme Immunoassay in Liver and Renal Transplant Recipients
    Therapeutic Drug Monitoring, 2020
    Co-Authors: Ian S. Westley, Paul Salm, Paul J Taylor, Raymond G. Morris
    Abstract:

    The immunosuppressant drug tacrolimus has a narrow therapeutic index and is subject to a large variation in individual bioavailability and clearance. With its narrow therapeutic index, therapeutic drug monitoring is standard clinical practice in the management of transplant recipients. In this study, we report the evaluation of the cloned Enzyme donor Immunoassay (CEDIA) for the determination of whole-blood tacrolimus concentrations compared with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and Microparticle Enzyme Immunoassay (MEIA) using samples obtained from liver (n = 100) and renal (n = 88) transplant recipients. Linear regression analysis showed a relationship of CEDIA = 1.24 HPLC-MS/MS -0.18 (r(2) = 0.81). The mean bias ( +/-SEM) for all patients when compared with HPLC-MS/MS was 22.2% ( +/-2.1%). The precision of the CEDIA method for all samples showed a root mean square error of 3.1 mu g/L. Liver transplant recipient samples showed a mean (+/-SEM) bias compared with HPLC-MS/MS of 12.5% ( +/-1.6%). The precision of the CEDIA method for these samples showed a root mean square error of 1.5 mu g/L. The data suggest that in the renal transplant group, the CEDIA and MEIA methods have a bias of 33.3% and 20.1%, respectively, compared with HPLC-MS/MS. The CEDIA tacrolimus Immunoassay has been shown to be a rapid method for the determination of whole-blood tacrolimus concentrations and may be considered when HPLC-MS/MS is not available. When used in the clinical setting with other parameters, it would be a useful adjunct in the management of liver transplant recipients, but a significant bias in renal transplant patients needs to be further investigated.

  • Tacrolimus Measurement by Microparticle Enzyme Immunoassay Ii
    Therapeutic Drug Monitoring, 2003
    Co-Authors: Paul J Taylor, Raymond G. Morris
    Abstract:

    PJ Taylor and RG Morrishttp://www.ncbi.nlm.nih.gov/pubmed/1276654

  • evaluation of Microparticle Enzyme Immunoassay against hplc mass spectrometry for the determination of whole blood tacrolimus in heart and lung transplant recipients
    Clinical Biochemistry, 2000
    Co-Authors: Paul Salm, David M Rutherford, Paul J Taylor, Marion Black, P Pillans
    Abstract:

    Objectives: Tacrolimus is an immunosuppressant drug with a narrow therapeutic window and thus requires therapeutic drug monitoring. This study evaluates the suitability of the second-generation Microparticle Enzyme Immunoassay (MEIA II) against a specific method, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS), for the measurement of tacrolimus in both heart- and lung-transplant groups. A secondary objective was to investigate the effect of tacrolimus concentration on MEIA II measurement.

  • analytical performance of Microparticle Enzyme Immunoassay and hplc tandem mass spectrometry in the determination of sirolimus in whole blood
    Clinical Chemistry, 1999
    Co-Authors: Paul Salm, Paul J Taylor, P Pillans
    Abstract:

    The potent immunosuppressant agent sirolimus (rapamycin; Wyeth-Ayerst) is undergoing clinical trials in solid-organ transplantation (1)(2). Evidence suggests that therapeutic drug monitoring of trough sirolimus concentrations may be beneficial for two fundamental reasons: (a) a strong correlation between the trough concentration and the area under the concentration-time curve has been shown; and (b) a strong correlation between the evidence of toxicity and trough concentrations substantially >15 μg/L has been reported (3). To date, there have been only HPLC methods available to measure sirolimus in human whole blood. These include HPLC with mass spectrometric detection (4)(5) and HPLC with ultraviolet detection (6)(7)(8)(9). As an alternative, a semiautomated method utilizing the IMx analyzer (Abbott Diagnostics) that incorporates Microparticle Enzyme Immunoassay (MEIA) technology has been developed. There are two versions of the MEIA for sirolimus in whole blood, the prototype version (Mode 1A) and the recently manufactured premarket version (Mode 1C). Both of these assays are undergoing evaluation based on their analytical performance and clinical use. This study compares the analytical performance of the prototype MEIA (Mode 1A) with HPLC-tandem mass spectrometry (HPLC-MS) within one center through evaluation of interference with endogenous and exogenous compounds, imprecision, recovery, and the quantification range. In addition, blood samples from renal transplant patients receiving sirolimus therapy are compared using both methods. Throughout this study, HPLC-MS was performed as per our reported method (4) and MEIA according to manufacturer’s instructions. All patient specimens were stored at −75 °C until analysis. Investigation into potential interferences in HPLC-MS and MEIA in relation to endogenous compounds was determined based on 209 samples collected into EDTA tubes from 23 renal transplant recipients …

Pierre Wallemacq - One of the best experts on this subject based on the ideXlab platform.

  • IMx Tacrolimus II vs IMx Tacrolimus Microparticle Enzyme Immunoassay Evaluated in Renal and Hepatic Transplant Patients
    Clinical Chemistry, 1997
    Co-Authors: Pierre Wallemacq, Teresinha Leal, T. Besse, Jean-paul Squifflet, Raymond Reding, Jean-bernard Otte, Jan Lerut, A. Hassoun
    Abstract:

    In 1992, an automated whole-blood Microparticle Enzyme Immunoassay was developed (Abbott Labs.) for the measurement of tacrolimus concentrations (TAC I) on the IMx analyzer (1). This method involves the antitacrolimus monoclonal antibody developed by Fujisawa Pharmaceutical, the company producing the immunosuppressant tacrolimus (2). The assay requires 100 μL of whole blood, and 24 samples can be analyzed in ∼40 min after a rapid organic extraction (200 μL of precipitation reagent: ZnSO4 solution in methanol and ethylene glycol). The capture reagent consists of latex Microparticles to which tacrolimus antibodies are attached, the Enzyme is tacrolimus-conjugated alkaline phosphatase, and the substrate is 4-methylumbelliferyl phosphate. This method yields CVs of ∼10% (11.8% and 9.6% at concentrations of 15 and 25 μg/L, respectively) (1), but is limited by the detection limit of 5 μg/L. Because in current clinical practice a nonnegligible percentage of transplant patients display low tacrolimus concentrations (

  • imx tacrolimus ii vs imx tacrolimus Microparticle Enzyme Immunoassay evaluated in renal and hepatic transplant patients
    Clinical Chemistry, 1997
    Co-Authors: Pierre Wallemacq, Teresinha Leal, T. Besse, Jean-paul Squifflet, Raymond Reding, Jean-bernard Otte, Jan Lerut, A. Hassoun
    Abstract:

    In 1992, an automated whole-blood Microparticle Enzyme Immunoassay was developed (Abbott Labs.) for the measurement of tacrolimus concentrations (TAC I) on the IMx analyzer (1). This method involves the antitacrolimus monoclonal antibody developed by Fujisawa Pharmaceutical, the company producing the immunosuppressant tacrolimus (2). The assay requires 100 μL of whole blood, and 24 samples can be analyzed in ∼40 min after a rapid organic extraction (200 μL of precipitation reagent: ZnSO4 solution in methanol and ethylene glycol). The capture reagent consists of latex Microparticles to which tacrolimus antibodies are attached, the Enzyme is tacrolimus-conjugated alkaline phosphatase, and the substrate is 4-methylumbelliferyl phosphate. This method yields CVs of ∼10% (11.8% and 9.6% at concentrations of 15 and 25 μg/L, respectively) (1), but is limited by the detection limit of 5 μg/L. Because in current clinical practice a nonnegligible percentage of transplant patients display low tacrolimus concentrations (<6 μg/L), the Immunoassay has recently been modified. A new assay, IMx tacrolimus II (TAC II), with a lower detection limit, has been developed, requiring 150 μL of whole blood and 150 μL of precipitation reagent. Whereas the TAC I has a dynamic range of quantification from 5 to 60 μg/L, the TAC II assay has a range from 1 to 30 μg/L, better corresponding to the therapeutic range of tacrolimus (5–15 μg/L) (3). Because this new assay will replace the TAC I, we have evaluated and compared the two assays in terms of their analytical performances, and their correlation in clinical blood specimens obtained from kidney and liver transplant patients. Analytical performances were evaluated on the same IMx analyzer, by the same technician, and on the same days. The pipettes used were calibrated before the study. All the analyses (mode 1 calibrator, …

  • hplc Microparticle Enzyme Immunoassay specific for tacrolimus in whole blood of hepatic and renal transplant patients
    Clinical Chemistry, 1995
    Co-Authors: I Firdaous, T. Besse, Jean-paul Squifflet, Raymond Reding, Jean-bernard Otte, A. Hassoun, Pierre Wallemacq
    Abstract:

    Tacrolimus is a relatively new immunosuppressant used in organ transplantation to prevent graft rejection. However, its use is not devoid of side effects, making it important to maintain blood concentrations within therapeutic ranges. Several analytical methods are currently available for routine drug monitoring. However, these methods are based on use of the same monoclonal antibody, which also cross-reacts with some metabolites, resulting in overestimation of some blood concentrations. Even though this antibody appears appropriate for therapeutic drug monitoring, no reference method measures only the parent drug, mainly because of the poor absorptivity of tacrolimus in ultraviolet light. We have developed a method displaying an increased specificity towards the unchanged drug, using conventional equipment available in most clinical laboratories. After chromatographic separation of the blood extract, the tacrolimus fraction is analyzed by an automated Microparticle Enzyme Immunoassay (MEIA) performed on the IMx analyzer (Abbott Labs.). This method is linear from 0 to 40 micrograms/L, yields CVs from 8.5% to 18.2%, and has a detection limit of 5 micrograms/L. Tacrolimus concentrations obtained by HPLC-MEIA in hepatic and renal transplant patients are from 47.5% to 18.8% lower than those obtained by MEIA, according to liver function tests and metabolite accumulation, even though no significant differences were observed between the methods for drug-free blood samples supplemented with known amounts of tacrolimus.

Paul Salm - One of the best experts on this subject based on the ideXlab platform.

  • The quantification of sirolimus by high-performance liquid chromatography-tandem mass spectrometry and Microparticle Enzyme Immunoassay in renal transplant recipients
    Clinical Therapeutics, 2020
    Co-Authors: Paul Salm, Paul J Taylor, P Pillans
    Abstract:

    Abstract Background Sirolimus, an immunosuppressive agent, is undergoing clinical trials in the prophylaxis of organ rejection. Objectives The aim of this study was to compare the performance of the semi-automated prototype (mode 1 A) Microparticle Enzyme Immunoassay (MEIA) against a validated high-performance liquid chromatography-mass spectrometry (HPLC-MS) method for measuring sirolimus concentrations. A secondary objective was to identify potential factors that may influence sirolimus measurement. Methods The comparison was based on predose samples (n = 841) from 74 renal transplant patients receiving sirolimus therapy. Samples were collected up to 12 months after transplantation. Results The mean (± SD) overestimation by MEIA was 42.5% ± 16.9%. Several variables were investigated to determine potential contributors to the observed overestimation. Stratification of the data based on the mean sirolimus concentrations determined by both assays yielded no statistically significant differences in bias between concentration subgroups within the clinically relevant range. Multiple linear regression analysis identified HPLC-MS sirolimus concentration ( P = 0.03), hemoglobin concentration ( P P Conclusion The MEIA overestimates sirolimus concentrations in renal transplant patients compared with HPLC-MS. The clinical importance of this observed overestimation requires further investigation.

  • Cloned Enzyme Donor Immunoassay Tacrolimus Assay Compared With High-Performance Liquid Chromatography-Tandem Mass Spectrometry and Microparticle Enzyme Immunoassay in Liver and Renal Transplant Recipients
    Therapeutic Drug Monitoring, 2020
    Co-Authors: Ian S. Westley, Paul Salm, Paul J Taylor, Raymond G. Morris
    Abstract:

    The immunosuppressant drug tacrolimus has a narrow therapeutic index and is subject to a large variation in individual bioavailability and clearance. With its narrow therapeutic index, therapeutic drug monitoring is standard clinical practice in the management of transplant recipients. In this study, we report the evaluation of the cloned Enzyme donor Immunoassay (CEDIA) for the determination of whole-blood tacrolimus concentrations compared with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and Microparticle Enzyme Immunoassay (MEIA) using samples obtained from liver (n = 100) and renal (n = 88) transplant recipients. Linear regression analysis showed a relationship of CEDIA = 1.24 HPLC-MS/MS -0.18 (r(2) = 0.81). The mean bias ( +/-SEM) for all patients when compared with HPLC-MS/MS was 22.2% ( +/-2.1%). The precision of the CEDIA method for all samples showed a root mean square error of 3.1 mu g/L. Liver transplant recipient samples showed a mean (+/-SEM) bias compared with HPLC-MS/MS of 12.5% ( +/-1.6%). The precision of the CEDIA method for these samples showed a root mean square error of 1.5 mu g/L. The data suggest that in the renal transplant group, the CEDIA and MEIA methods have a bias of 33.3% and 20.1%, respectively, compared with HPLC-MS/MS. The CEDIA tacrolimus Immunoassay has been shown to be a rapid method for the determination of whole-blood tacrolimus concentrations and may be considered when HPLC-MS/MS is not available. When used in the clinical setting with other parameters, it would be a useful adjunct in the management of liver transplant recipients, but a significant bias in renal transplant patients needs to be further investigated.

  • evaluation of Microparticle Enzyme Immunoassay against hplc mass spectrometry for the determination of whole blood tacrolimus in heart and lung transplant recipients
    Clinical Biochemistry, 2000
    Co-Authors: Paul Salm, David M Rutherford, Paul J Taylor, Marion Black, P Pillans
    Abstract:

    Objectives: Tacrolimus is an immunosuppressant drug with a narrow therapeutic window and thus requires therapeutic drug monitoring. This study evaluates the suitability of the second-generation Microparticle Enzyme Immunoassay (MEIA II) against a specific method, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS), for the measurement of tacrolimus in both heart- and lung-transplant groups. A secondary objective was to investigate the effect of tacrolimus concentration on MEIA II measurement.

  • analytical performance of Microparticle Enzyme Immunoassay and hplc tandem mass spectrometry in the determination of sirolimus in whole blood
    Clinical Chemistry, 1999
    Co-Authors: Paul Salm, Paul J Taylor, P Pillans
    Abstract:

    The potent immunosuppressant agent sirolimus (rapamycin; Wyeth-Ayerst) is undergoing clinical trials in solid-organ transplantation (1)(2). Evidence suggests that therapeutic drug monitoring of trough sirolimus concentrations may be beneficial for two fundamental reasons: (a) a strong correlation between the trough concentration and the area under the concentration-time curve has been shown; and (b) a strong correlation between the evidence of toxicity and trough concentrations substantially >15 μg/L has been reported (3). To date, there have been only HPLC methods available to measure sirolimus in human whole blood. These include HPLC with mass spectrometric detection (4)(5) and HPLC with ultraviolet detection (6)(7)(8)(9). As an alternative, a semiautomated method utilizing the IMx analyzer (Abbott Diagnostics) that incorporates Microparticle Enzyme Immunoassay (MEIA) technology has been developed. There are two versions of the MEIA for sirolimus in whole blood, the prototype version (Mode 1A) and the recently manufactured premarket version (Mode 1C). Both of these assays are undergoing evaluation based on their analytical performance and clinical use. This study compares the analytical performance of the prototype MEIA (Mode 1A) with HPLC-tandem mass spectrometry (HPLC-MS) within one center through evaluation of interference with endogenous and exogenous compounds, imprecision, recovery, and the quantification range. In addition, blood samples from renal transplant patients receiving sirolimus therapy are compared using both methods. Throughout this study, HPLC-MS was performed as per our reported method (4) and MEIA according to manufacturer’s instructions. All patient specimens were stored at −75 °C until analysis. Investigation into potential interferences in HPLC-MS and MEIA in relation to endogenous compounds was determined based on 209 samples collected into EDTA tubes from 23 renal transplant recipients …

  • High-Performance Liquid Chromatography-Tandem Mass Spectrometry as a Reference for Analysis of Tacrolimus to Assess Two Immunoassays in Patients With Liver and Renal Transplants
    Therapeutic Drug Monitoring, 1997
    Co-Authors: Paul Salm, Paul J Taylor, Andrea Clark, Glenda A. Balderson, Anthony Grygotis, Ross Norris, Stephen V. Lynch, Leslie M. Shaw, Susan M. Pond
    Abstract:

    The accuracy and imprecision of three assays used for therapeutic monitoring of tacrolimus were tested using blood-containing weighed-in amounts of the drug, an Enzyme-linked immunosorbent assay (ELISA), a Microparticle Enzyme Immunoassay (MEIA I), and a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS) assay. Accuracy was acceptable for the HPLC-MS assay at all concentrations tested ( 13%). The MEIA I had unacceptable bias (1.7-1.8 μg/l) and variability (SD > 23%). These data indicated that neither the ELISA nor MEIA I is interchangeable with HPLC-MS. Moreover, in view of the current trend to reduce the therapeutic dose of tacrolimus, quantitative results using the MEIA I would not be obtainable during therapeutic drug monitoring in some patients in whom effective therapeutic concentrations can be less than 5.0 μg/l.

Yukinao Kohda - One of the best experts on this subject based on the ideXlab platform.

  • Use of sample hematocrit value to correct blood tacrolimus concentration derived by Microparticle Enzyme Immunoassay.
    Biological & Pharmaceutical Bulletin, 2008
    Co-Authors: Takashi Tomita, Masato Homma, Yuichi Hasegawa, Hiroshi Kojima, Nobuhiro Ohkohchi, Tetsuo Hori, Michio Kaneko, Yasuko Nakano, Takashi Tobe, Yukinao Kohda
    Abstract:

    The quality of Microparticle Enzyme Immunoassay (MEIA) for blood tacrolimus is guaranteed in samples with hematocrit (Ht) values of 25 to 45%. Because MEIA provides inaccurate blood tacrolimus concentrations in samples with Ht out of this range (i.e. 45%), correction of the calibration is required for therapeutic drug monitoring. The authors demonstrated previously that overestimated MEIA tacrolimus concentration could be corrected by modified, calibrated MEIA (cMEIA) using the original calibrator. Here, an equation was established to more easily derive a corrected tacrolimus concentration by calculation (MEIAcalc) using the Ht of each sample. The tacrolimus concentrations of 99 whole-blood samples with low Ht (

  • effects of hematocrit value on Microparticle Enzyme Immunoassay of tacrolimus concentration in therapeutic drug monitoring
    Therapeutic Drug Monitoring, 2005
    Co-Authors: Takashi Tomita, Masato Homma, Kenji Yuzawa, Yuichi Hasegawa, Hiroshi Kojima, Nobuhiro Ohkohchi, Tetsuo Hori, Michio Kaneko, Toshiro Nagasawa, Yukinao Kohda
    Abstract:

    : The effects of hematocrit (Ht) value on Microparticle Enzyme Immunoassay (MEIA) of tacrolimus concentration were examined in 1063 whole-blood samples from 42 transplant recipients (13 liver, 20 kidney, and 9 bone marrow transplantations). MEIA guarantees the test's assay quality for blood tacrolimus in samples with Ht values of 25% to 45%. However, 129 samples (29.3%) obtained from liver transplant recipients and 107 samples (61.5%) from bone marrow transplant recipients had lower Ht ( 45% were observed in kidney transplant patients. Twenty-five whole-blood samples with low Ht were tested by 3 assay methods for tacrolimus: MEIA, modified, corrected MEIA (cMEIA), and Enzyme-linked immunosorbent assay (ELISA). MEIA gave higher blood concentrations of tacrolimus than ELISA (16.1 versus 11.0 ng/mL, P < 0.001). This difference was generated by overestimation in MEIA and was not observed in samples with normal Ht. This overestimation was eliminated by using cMEIA on samples with low Ht values: there was no difference in blood tacrolimus concentration between cMEIA and ELISA (12.3 versus 11.0 ng/mL). ELISA or cMEIA should be used for tacrolimus assay in samples obtained from bone marrow transplant recipients with anemia and from liver and kidney transplant recipients with unstable Ht values.

  • false positive blood tacrolimus concentration in Microparticle Enzyme Immunoassay
    Biological & Pharmaceutical Bulletin, 2002
    Co-Authors: Masato Homma, Takashi Tomita, Kenji Yuzawa, Yasutsugu Takada, Yukinao Kohda
    Abstract:

    The difference in the blood concentration of tacrolimus between the assay methods, Microparticle Enzyme Immunoassay (MEIA) and Enzyme linked immunosorbent assay (ELISA) was observed in a liver transplant recipient with anemia. MEIA provided significantly higher concentration than those of ELISA (7.8±1.9 vs. 5.0±1.8 ng/ml, p 25%. This observation suggested that unknown tacrolimus levels generated from difference in assay methods gave incorrect blood tacrolimus during anemia. False positive concentration of tacrolimus ranging 0.1—3.3 ng/ml was observed in MEIA applying to the blood samples obtained from the patients without receiving tacrolimus. The false positive tacrolimus increased in the samples with lower hematocrit, suggesting that MEIA gave incorrect blood tacrolimus during anemia. Since MEIA potentially overestimates the tacrolimus levels, ELISA should be used for blood tacrolimus monitoring in the patients with anemia.