Different Chromatographic Methods for the Determination of Antidiabetic Drugs in the Presence of Drug Toxic Impurity

Abstract

Two validated, simple, and precise chromatographic methods were described for the determination of vildagliptin (VIL) and metformin (MET) in the presence of metformin toxic impurity, melamine (MEL). Method 1 is thin-layer chromatography (TLC)—densitometric method, at which methanol—chloroform—formic acid (7:3:0.3, by volume) was used as the developing system, and separation was carried out on Merck TLC silica gel 60 F254 aluminum sheets. The developed plates were air-dried and scanned at 215 nm. Linearity was constructed in the range of 0.2–2.6, 0.4–4.5, and 0.05–1.4 µg per band of VIL, MET, and MEL, respectively. Method 2 is reversed-phase ultra-performance liquid chromatography (RP-UPLC), where the separation was performed on a C18 column using methanol-acetonitrile—0.01 m sodium dihydrogen phosphate solution containing 50% 0.01 m sodium lauryl sulfate, pH = 5 with H3PO4 as the mobile phase at a flow rate of 1 mL min−1 at 205 nm. The calibration curves showed good linear relationships in the concentration ranges of 1–50, 2–70, and 0.5–30 µg mL−1 of VIL, MET, and MEL, respectively. The developed methods were applied to Galvus Met® tablets, and no interference from excipients was observed. The methods were validated as per the International Conference on Harmonisation (ICH) guidelines, and they compared favorably with the reported one.