A validated HPLC-PDA method for simultaneous quantitation of four oral antidiabetic drugs and application to pharmaceutical preparations

A simple, rapid, and sensitive HPLC-PDA method has been developed for the simultaneous separation and estimation of metformin (MET), sitagliptin (SIT), glipizide (GPZ), and glibenclamide (GBN). The proposed method utilized Bondapak™ C18 (3.9×150 mm, 10 μm) column and the separation has been achieved within 10 min, with mobile phase consisted of methanol: phosphate buffer 0.05 M (60:40, v/v) adjusted to pH 5, delivered at a flow rate of 0.8 mL/min. Photodiode array detector was used to detect drugs at 260 nm. The developed method was validated according to the ICH guidelines. The method was linear over the range of 0.5-100, 0.5-10, 0.005-10, and 0.5-10 μg/mL for MET, SIT, GPZ, and GBN, respectively, with excellent correlation coefficients (r ≥ 0.9976). Intra-day and inter-day RSD values were ≤ 2.6. The recoveries of drugs from their tablets ranged from 97-103%. The proposed method was successfully applied to the analysis of MET, SIT, GPZ, and GBN in their tablets, and it is suitable for the rapid quantitation of these drugs in single or combined dosage forms. (author)