Determination of Metformin and Vildagliptin in Solid Dosage Form and Rabbit Plasma by HPLC: An Application to Pharmacokinetic Study

The present work aimed to validate a simple and rapid method for simultaneous determination of metformin hydrochloride (MTF) and vildagliptin (VLD) in tablet in addition to a pharmacokinetic study in rabbit plasma. Isocratic elution of both the analytes was performed at 35 degrees C by injecting 20 mu L into Thermo Hypersil ODS C18 column (5 mu m, 4.6 x 250 mm) while the flow rate was set to 0.8 mL/min. The mobile phase comprised of methanol, acetonitrile and phosphate buffer (5:30:65, v/v, pH 3.5) and wavelength was selected at 212 nm. The overall run time per sample was 7.0 min with retention time of 336 and 5.41 min for MTF and VLD, respectively. The calibration curve was linear from 10-140 mu g/mL for MTF and 1-14 mu g/mL for VLD with R-2 (coefficient of determination) <= 0.9919 while % RSD was less than 1.13 and 0.97 %, respectively, for repeatability and reproducibility. The proposed RP-HPLC method showed accuracy providing recoveries ranged between 100.13-100.29 %. For pharmacokinetic study, the proposed method successfully determined the MTF and VLD concentration in plasma after oral administration of both drugs to healthy and diabetic induced rabbits.