A sensitive and selective liquid chromatography mass spectrometry method for simultaneous estimation of anti-diabetic drugs inhibiting DPP-4 enzyme in human plasma: overcoming challenges associated with low recovery and sensitivity†
DPP-4 inhibitors (gliptins) have shown better glycaemic control even in more feeble cases such as elderly people, patients with high cardiovascular and hypoglycaemic risk and individuals with renal impairment. However, the plasma concentrations of selected drugs has to be estimated to correlate those results with various uncertainties during clinical studies. A simple and sensitive LC-QTOF/MS method was developed and validated to measure the human plasma concentrations of vildagliptin, saxagliptin, sitagliptin, linagliptin and teneligliptin, using pioglitazone as an internal standard. Chromatographic separation of five gliptins was achieved on a Zorbax Eclipse Plus C-18 column Rapid Resolution HD (50 × 2.1 mm, 1.8 μm) using a mobile phase consisting of 20 mM ammonium formate and acetonitrile in gradient mode. Detection was performed with positive ion electrospray ionization mass spectrometry using target ions in selective ion mode. Simpler protein precipitation was employed for sample extraction from human plasma. The low recovery of gliptins observed due to non-specific binding to glass was surpassed by using polypropylene. The mean recovery was found to be 96.82 ± 1.03% (VIL), 94.32 ± 0.74% (SAX), 95.37 ± 2.09% (SIT), 91.67 ± 3.14% (LIN) and 93.29 ± 1.03% (TEN) respectively. The proposed method will serve as an excellent tool for various clinical studies like therapeutic drug monitoring, pharmacokinetics, toxicological and protein binding studies.