New UPLC–MS/MS Assay for the Determination of Tamoxifen and Its Metabolites in Human Plasma, Application to Patients

Abstract

Aim: A rapid UPLC–MS/MS method for the determination of tamoxifen (TAM), N -desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in human plasma was validated, after a simple protein precipitation. Materials and methods: The analysis was achieved on a C 18 analytical column, using a gradient elution with a mobile phase of water and acetonitrile for 4.5 min. Results: The validated method demonstrated good linearity between 1 and 500 ng/ml for TAM and N -desmethyltamoxifen; between 0.2 and 100 ng/ml for endoxifen and between 0.1 and 50 ng/ml for 4-hydroxytamoxifen. The method also provided satisfactory results in terms of within day and between day imprecisions and accuracy, and also in terms of time stability and specificity. Conclusion: The method is applied routinely for TAM monitoring from patients undergoing therapy.

Enhancing Solid-Phase Extraction of Tamoxifen and Its Metabolites from Human Plasma Using MOF-Integrated Polyacrylonitrile Composites: A Study on CuBTC and ZIF-8 Efficacy

“…The presence of high-intensity (011), (002), (112), (022), (013), and (222) peaks verified the presence of ZIF-8 in the PAN nanofibers. These results are in agreement with preview reports [ 43 , 44 ]. For both MOFs, the XRD patterns evidence the crystal stability to endure the complete electrospinning process, from the stirring, mixing, relatively high temperatures, rapid solvent evaporation, and high electrostatic fields.…”

“…Retention times and multiple reactions monitoring transitions for TAM, NDTAM, ENDO, and 4OHT metabolites and internal standards TAM-d5, ENDO-d5, and 4OHT-d5. References [ 44 , 45 ] are cited in the supplementary materials.…”

Targeting hormone-resistant breast cancer cells with docetaxel: a look inside the resistance

“…The level of 17β-estradiol undergoes significant changes in premenopausal women; usually, the level of this hormone is between 30 and 400 pg/mL [34][35][36][37] . Thus, we cannot talk about an average level of 17β-estradiol in plasma; in experimental studies, most researchers apply a dose of 17β-estradiol that induces the expression of responsive genes, 10 nM or 2.7 ng/mL [38,39] . We see similar trends for antiestrogens, which are used as 17β-estradiol competitors (selective estrogen receptor modulators, SERMs).…”

“…We see similar trends for antiestrogens, which are used as 17β-estradiol competitors (selective estrogen receptor modulators, SERMs). In the plasma of breast cancer patients who receive tamoxifen, from 391 to 484 ng/mL of the major metabolites of this drug (tamoxifen, N-desmethyltamoxifen, hydroxytamoxifen, endoxifen) were determined [ 40 , 41 ] . In in vitro experiments, the IC 50 values of tamoxifen usually exceed the level of 500 ng/mL and were 1-20 µg/mL [ 42 - 44 ] .…”

Long-Term Oral Tamoxifen Administration Decreases Brain Derived Neurotrophic Factor in the Hippocampus of Female Long-Evans Rats

“…Analytes were separated using a gradient elution, with retention time of 2.68 min for tamoxifen and tamoxifen-d5. The LC-MS Tamoxifen assay used here was based on assays initially developed and validated in human plasma (Bobin-Dubigeon et al, 2019;Rama Raju et al, 2015). Therefore, as a confirmatory assay, human plasma and rat plasma were compared using 100 ng/mL concentrations of tamoxifen and found to be comparable ( At the conclusion of the experiment, subjects were sacrificed by intracardial perfusion.…”