A Simple Stability-Indicating LC-UV Method to Assay Sitagliptin Phosphate in Tablets

This paper describes the development and validation of an isocratic LC-UV method for the assay of sitagliptin phosphate in tablets, a drug recently approved for the treatment of type 2 diabetes mellitus (DM). The method employs a Phenomenex((R)) C18 column (150mm x 4.6mm I.D., 5 mu m) with 0.025 M phosphate buffer pH 6.8: acetonitrile (60:40, v/v) as mobile phase, at a 0.8 mL min(-1) flow rate and UV detection at 267 nm. The chromatographic separation was obtained within a retention time of 3.7 min. The method was linear (r = 0.9999) in the range of 25-75 mu g. mL(-1). The method's specificity and stability-indicating capability were proved through force degradation studies, being the peak purity evaluated by PDA detector. Sitagliptin phosphate was exposed to oxidative, hydrolytic and photolytic stress conditions, and no interference from degradation products was observed. The method has shown good and consistent recoveries (mean value 100.0%) with low intra and inter-day relative standard deviation (RSD). In robustness study, it was observed that peak area was unaffected by small changes in critical factors. The validated method can be successfully applied to determine sitagliptin in tablets and in stability studies.