Objective: This study aimed to analyze doxorubicin and doxorubicinol levels in Dried Blood Spot (DBS) from 25 breast cancer patients who received doxorubicin in their therapeutic regiment. Methods: DBS samples were extracted by protein precipitation method and analyzed using Ultra Performance Liquid Chromatography tandem Mass Spectrometry (LC-MS/MS), with the Acquity UPLC BEH C18 Waters chromatography column (2.1 x 100 mm x 1.7 μm). The mobile phase consisted of 0.1% acetic acid (eluent A) and acetonitrile (eluent B) with gradient elution; the flow rate was 0.15 ml/min and runtime, 7 min. This method was linear within the concentration range of 10–200 ng/ml for doxorubicin and 4–100 ng/ml for doxorubicinol. Result: The analysis results showed that doxorubicin levels were in the range of 11.01 ng/ml to 93.75 ng/ml and doxorubicinol was 5.80 ng/ml to 58.57 ng/ml. Conclusion: Cumulative doses of all patients were in the range of 49.11 mg/m2to 303.70 mg/m2, which have cardiomyopathy incidence rates<4%.

A BSTRACT Dried blood spot as biosampling method offers a less invasive and easier procedure. This study aimed to develop the validated analytical method of doxorubicin hydrochloride and doxorubicinol simultaneously in dried blood spot with hexamethylphosphoramide as the internal standard. A total of 30 μL blood was spotted on DBS paper and dried for 3 hours before it was extracted by protein precipitation method using water and methanol. The separation was performed on column Acquity UHPLC BEH C-18 (2.1 × 100 mm; 1.7 μm), with 0.15 mL/min flow rate and using 0.1% acetic acid and acetonitrile as mobile phase in gradient elution for 7 min. Quantification analysis was performed by a triple quadrupole mass spectrometry with electrospray ionization (ESI) in positive ion mode. The multiple reaction monitoring (MRM) was set at m/z 544.22 > 397.06 for doxorubicin hydrochloride; m/z 546.22 > 361.05 for doxorubicinol; and m/z 180.03 > 135.16 for hexamethylphosphoramide. The lower limit of quantitation was 10 ng/mL for doxorubicin and 4 ng/mL for doxorubicinol. Concentration range acquired was 10–200 ng/mL for doxorubicin and 4–100 ng/mL for doxorubicinol. The precision and accuracy were within acceptable criteria of <15%. Dried blood spot samples acquired was stable for at least 30 days before analysis. This method fulfilled the validation requirement refers to Bioanalytical Method Validation Guideline of European Medicines Agency 2011 and US Food and Drug Administration 2018.