Background:Tamoxifen is a selective estrogen cancer receptor modulators (SERMs) breast cancer drug that binds to estrogen (ER) receptors. Tamoxifen metabolized by CYP2D6 enzymes into more active metabolites, including N-desmethyltamoxifen, 4-hydroxitamoxifen, and 4-hydroxy-N-desmethyltamoxifen (endoxifen). So far the analytical method can be done using the bioanalysis method using plasma samples and whole blood samples using the finger prick biosampling method. Finger prick biosampling can be done with Dried Blood Spot (DBS) and Volumetric Absorbtive Microsamplings (VAMS). Objective:This study aimed to compare the parameters of peak area ratio, recovery, selectivity, matrix effect, and stability to the analysis of tamoxifen and its metabolites between DBS Perkin Elmer 226 and VAMS Neoteryx MITRA®. Materials and Methods:Sample preparation was done by solvent extraction method and sonication-assisted extraction using methanol as extraction solvent. Separation was performed with a reverse phase chromatography using the Acquity UPLC BEH C18 column (2.1 x 100 mm; 1.7 mm), with a flow rate of 0.2 mL/minute, and under a mobile phase gradient of formic acid 0.1% and acid formate 0.1% in acetonitrile for 5 minutes. Quantitative analysis of analytes was performed using triple quadrupole mass spectrometry with electrospray ionization (ESI) in positive ion mode. The multiple reaction monitoring (MRM) was set at m/z 372.2> 72.27 for tamoxifen, 388.29> 72.19 for 4-hydroxitamoxifen, 374.29> 58.2 for endoxifen and m/z 260.2> 116.2 for propranolol hydrochloride as internal standard. Results:The results showed that there were significant differences in the value of the peak area ratio (p <0.05), recovery (p <0.05), and matrix effects (p <0.05). Conclusion:Overall, the results of the analysis using VAMS biosampling Neoteryx MITRA® gave better results than DBS Perkin Elmer 226.

Key words:4-hydroxytamoxifen, dried blood spot, endoxifen, LC-MS/MS, N-desmethyltamoxifen, propranolol, tamoxifen, volumetric absorbtive microsampling