The discovery of potent antidiabetic drugs is of necessity owing to the rapid prevalence of diabetes worldwide. The investigation of a new separation method for the simultaneous determination of combined antidiabetic drugs is thus an essential issue to cover the usual demands of simple analytical methods for the routine analysis. Therefore, herein, simple and fast chromatographic methods were established for synchronized determination of metformin (MET) and dapagliflozin (DAP), a mixture approved recently by the Food and Drug Administration (FDA) for diabetes therapy. In high-performance liquid chromatography (HPLC), a Water-pak C18 column was used as the stationary phase with an isocratic mobile phase composed of 10 mM NaH2PO4 (pH 3.5 adjusted using ortho-phosphoric acid)—acetonitrile (65:35, v/v) containing 0.1% trimethylamine at a flow rate of 1.2 mL min−1 and a wavelength detector set at 225 nm. In high-performance thin-layer chromatography (HPTLC), separation was achieved on pre-coated silica gel 60 F254 aluminum plates using acetonitrile—ammonium acetate 10%—acetic acid (9:0.9:0.1, v/v). The proposed methods were validated in the light of the International Conference on Harmonization (ICH) guidelines, and it was found that the two chromatographic methods are accurate, precise, and linear in the range of 2–20 µg mL−1 and 1–10 µg per spot for DAP and 20–400 µg mL−1 and 10–100 µg per spot for MET by HPLC and HPTLC, respectively. The methods achieved a reasonable sensitivity as shown by the low limit of detection ranging from 0.58 to 6.1 µg mL−1 and 0.314 to 3.1 µg per spot for HPLC and HPTLC, respectively. The validated methods succeeded in detecting the cited drugs in pharmaceutical formulation without interference of excipients. Although HPLC method is the most applicable method, HPTLC method exhibits a superior sensitivity and is cheap and fast allowing the determination of a large number of samples in due time.
