UHPLC Method Development for Determining Sitagliptin and Dapagliflozin in Lipid-Based Self-Nanoemulsifying Systems as Combined Dose in Commercial Products and its Application to Pharmacokinetic Study of Dapagliflozin in Rats

Anew simple, precise, selective and reproducible reversed-phase ultra-high performance liquid chromatography (RP-UHPLC) method has been developed and validated for the first time in simultaneous determination of two anti-diabetic drugs, sitagliptin (SN) and dapagliflozin (DN), in lipid-based self-nanoemulsifying formulations as a new combined preparation dose. The chromatographic separation was carried out on a reversed-phase Acquity^® BEH C₁₈ column using methanol–acetonitrile–water mixture at 24/18/58 (%v/v/v) ratio as the mobile phase. The isocratic flow rate was 0.4 mL/min with a run time of 6 min. The UV detection of both SN and DN was performed at 210 nm. The method was validated over a concentration range of 100 – 10000 ng/mL (r² = 0.9997 and 0.9999 for SN and DN, respectively). The selectivity, specificity, recovery, accuracy and precision for determining SN and DN in lipid-based formulation were validated. The lower limits of detection and quantitation of the method were 27 and 89 ng mL^–1 for SN and 19 and 61 ng mL^–1 for DN, respectively. The intra- and inter-day coefficients of variation were less than 4%. The validated method has been successfully applied to quantify both SN and DN in self-nanoemulsifying formulation of combined dosage form. In addition, the proposed method was also applied for in vivo pharmacokinetic study using an animal model (rat) to further illustrate the scope and application of the proposed method.