Abstract

This study focused on developing a robust chromatographic method to overcome the analytical challenges posed by the significant physicochemical differences and disproportionate dosage ratios of metformin, glimepiride, and pioglitazone. A Zorbax CN column (150mm×4.6mm, 5μm) was employed to achieve efficient separation, using a mobile phase comprising 54% acetonitrile and 46% ammonium acetate buffer (20mM, pH adjusted to 5.5). The flow rate was maintained at 1.0mL/min. A wavelength of 240nm was used for detecting glimepiride and pioglitazone, while the detection wavelength was switched to 265nm after 5.0 minutes for metformin. The method was optimized using a 2³ factorial design, ensuring high precision and accuracy within a short analysis time. The separation was completed in under 6.0 minutes. Excellent precision was demonstrated, with percent Relative Standard Deviations (%RSD) for both repeatability and intermediate precision well below 2%. The method also exhibited high accuracy, with analyte recoveries from commercial samples closely matching their labelled claims. The linearity ranges were 4-20μg/mL for pioglitazone, 6-30μg/mL for glimepiride, and 30-150μg/mL for metformin hydrochloride, with respective Limits of Detection (LOD) of 0.22μg/mL, 0.10μg/mL and 27.51μg/mL. This optimized method offers a precise, accurate and efficient solution for the simultaneous determination of these drugs.

Keywords:Glimepiride; Pioglitazone; Metformin; Pharmaceutical; Factorial design; Chromatography; HPLC