Quantification of Tacrolimus and Three Demethylated Metabolites in Human Whole Blood Using LC–ESI–MS/MS

Abstract

An LC-ESI-MS/MS method for the quantitative analysis of TAC and 3 metabolites, using a 2-step sample preparation was successfully developed, validated, and applied on 53 patient samples.

Validation of an LC–MS/MS Method to Measure Tacrolimus in Rat Kidney and Liver Tissue and Its Application to Human Kidney Biopsies

“…Due to the difficulty in obtaining sufficient quantities of drug-free human kidney tissue, TAC concentrations were calculated using calibrators prepared with rat kidney tissue. 29 Nonetheless, these preliminary observations may reflect large interindividual variability in the factors determining distribution of TAC from blood to tissue, including transporters 30 and protein binding 31 and a larger clinical study is necessary to further investigate the tissue pharmacokinetics of TAC. 4).…”

Commensal gut bacteria convert the immunosuppressant tacrolimus to less potent metabolites

“…Of note, certain tacrolimus metabolites (e.g., 13-O-demethyltacrolimus), independently of their immunosuppressive activities, crossreact with the antibodies used in the immunoassays for measurement of tacrolimus blood concentrations, leading to overestimation of tacrolimus concentrations. 1,22 Interestingly, such overestimation could not be fully explained by the cross-reactivity of currently known tacrolimus metabolites. 22 Whether the novel metabolite M1 cross-reacts with the antibodies, accounting in part for the overestimation of tacrolimus concentrations, is currently being investigated.…”

“…1,22 Interestingly, such overestimation could not be fully explained by the cross-reactivity of currently known tacrolimus metabolites. 22 Whether the novel metabolite M1 cross-reacts with the antibodies, accounting in part for the overestimation of tacrolimus concentrations, is currently being investigated.…”

Recent advances in analytical methods for the therapeutic drug monitoring of immunosuppressive drugs

“…Increased LC–MS/MS selectivity was also achieved in several recent papers by simultaneously measuring immunosuppressants and their major metabolites . MPA glucuronide (MPAG) is the major MPA metabolite that can be found in high concentrations in plasma, while MPA acyl‐glucuronide (AcMPAG) is a metabolite that is usually present at lower concentrations and has been implicated in some MPA adverse effects.…”

“…This simple assay is compatible with a routine process and may replace the current quantification method for the measurement of MPA, especially as the determination of MPA metabolites could improve MPA TDM efficiency. Dubbelboer et al successfully developed and validated an LC–ESI–MS/MS method for the quantitative analysis of TAC and its three metabolites, 13‐O, 15‐O, and 31‐O‐demethylated TAC (M‐I, M‐III, and M‐II, respectively), in human whole blood. The analytes were extracted by protein precipitation and a SPE, and the TAC concentration measured by LC–MS/MS was lower than that using an immunochemical (ie, enzyme multiplied immunoassay) method.…”