Spectrodensitometric and ultra-performance liquid chromatographic quantification of dapagliflozin and saxagliptin in their dosage form and human plasma

Purpose: To simultaneously quantify dapagliflozin (DAPA) and saxagliptin (SAX) in a pharmaceutical product and human plasma. Methods: Separation and quantification of DAPA and SAX were performed on pre-coated TLC plates in TLC-densitometric method using a solvent system of chloroform, ethyl acetate and methanol at a volume ratio of 8:1:1 as the mobile phase. The developed spots were scanned at 225 and 210 nm in absorbance mode. Moreover, the studied drugs were concurrently determined in human plasma using ultra-performance liquid chromatography (UPLC). The separation process was carried out in Waters^TM Acquity C18 BEH column using a solvent system of 0.02 M KH2PO4 buffer, pH 4; MeOH and acetonitrile (2:1:1, v:v:v) isocratically at a flow speed of 0.5 mL/min. The absorbance of each eluent was read at 220 nm. Results: Concurrent evaluation of DAPA and SAX was carried without separation using TLC-densitometric method, and it was successful in determination of DAPA and SAX in concentration ranges of 10 - 70 µg/band and 5 - 60 µg/band, respectively. In addition, retardation factor (Rf) values for SAX and DAPA were 0.17 and 0.31, respectively. Furthermore, the studied drugs were concurrently determined in human plasma using UPLC, which was sensitive enough to quantify DAPA and SAX in concentration ranges of 100 - 1000 and 20 - 200 ng/mL, respectively. Conclusion: These methods can be utilized for sensitive monitoring of DAPA and SAX in pharmacokinetic and bioequivalence studies.