13-O-Desmethyl tacrolimus (13-DMT; 13-O-Demethyl FK 506) is the major metabolite of Tacrolimus formed via cytochrome P450 3A-mediated biotransformation. The ratio of 13-O-Desmethyl tacrolimus to Tacrolimus serves as a biomarker for myelotoxicity and hepatotoxicity [1] [2].
In Vitro, 13O-Desmethyl tacrolimus (0.25-50 ng/mL) is accurately and precisely quantified in in vitro spiked rat kidney tissue homogenates via the validated LC-MS/MS assay, with stable performance through freeze-thaw cycling, 6 hours at room temperature, and 24 hours in the auto-sampler[2].
References:
[1]. Zegarska J, et al. Evaluation of the Relationship Between Concentrations of Tacrolimus Metabolites, 13-O-Demethyl Tacrolimus and 15-O-Demethyl Tacrolimus, and Clinical and Biochemical Parameters in Kidney Transplant Recipients. Transplant Proc. 2018 Sep;50(7):2235-2239.
[2]. Kirresh T, et al. Development and validation of a liquid chromatography-mass spectrometric assay for simultaneous determination of tacrolimus and 13-O-desmethyl tacrolimus in rat kidney tissue. Journal of pharmaceutical and biomedical analysis. 2017 Mar 20;136:32-37.
In Vitro, 13O-Desmethyl tacrolimus (0.25-50 ng/mL) is accurately and precisely quantified in in vitro spiked rat kidney tissue homogenates via the validated LC-MS/MS assay, with stable performance through freeze-thaw cycling, 6 hours at room temperature, and 24 hours in the auto-sampler[2].
References:
[1]. Zegarska J, et al. Evaluation of the Relationship Between Concentrations of Tacrolimus Metabolites, 13-O-Demethyl Tacrolimus and 15-O-Demethyl Tacrolimus, and Clinical and Biochemical Parameters in Kidney Transplant Recipients. Transplant Proc. 2018 Sep;50(7):2235-2239.
[2]. Kirresh T, et al. Development and validation of a liquid chromatography-mass spectrometric assay for simultaneous determination of tacrolimus and 13-O-desmethyl tacrolimus in rat kidney tissue. Journal of pharmaceutical and biomedical analysis. 2017 Mar 20;136:32-37.