Sensitive Spectrofluorimetric Methods for Determination of Sitagliptin Phosphate, Dipeptidyl Peptidase-4 Inhibitor, in Pharmaceutical Tablets and Spiked Human Urine

Background: Sitagliptin (SITA), is an oral anti-diabetic drug of dipeptidyl peptidase-4 (DPP-4) inhibitor class used as a monotherapy or in association with metformin to treat type II Diabetes Mellitus. Methods: Two new, sensitive and precise spectrofluorimetric methods have been developed for the determination of SITA in tablets and spiked human urine samples. SITA has a native fluorescence that was enhanced by 2 folds after addition of β-cyclodextrin (method A). The fluoregenic product was measured at 296 nm after excitation at 267 nm. In addition, SITA was derivatized by 7-chloro-4- nitrobenzofurazon (NBD-Cl) to a highly sensitive fluoregenic product was measured at 532 nm after excitation at 466 nm (method B). Results: The fluorescence intensities were directly proportional to the concentration over the range 0.35-10 μg mL-1 and 0.1-3 μg mL-1 for method A and B, respectively. The %RSD for inter-day and intra-day precisions was in a range of 0.16-0.92% and the accuracy results were in the range of 96.3% - 100.0%. Conclusion: Successful applications of the developed methods, for drug determination in pharmaceutical tablet and spiked human urine samples, were performed with high accuracy and precision.