STRESS STUDIES OF METFORMIN AND GLICLAZIDE BY HPLC METHOD AND EXTENSION OF METHOD APPLICATION FOR ELUTION OF SOME ANTIVIRAL, ANTI-BACTERIAL AND ANTI-INFLAMMATORY DRUGS

A simple reverse phase SI-HPLC method was developed for the simultaneous estimation of antidiabetic combination of metformin and gliclazide. The method was based on HPLC separation on a reversed-phase C18 column using a mobile phase consisting of phosphate buffer: acetonitrile (40:60, v/v) at a flow rate of 0.8 ml/min. UV determination was achieved at 240 nm. The analytes were subjected to various forced degradation following ICH guidelines. Degradation of metformin was observed under acidic, basic, and peroxide stress. Separation of all the degraded products was achieved. Method was linear in a concentration range of 100-700 µg/ml for metformin and 20-140 µg/ml for gliclazide. The limit of detection and quantitation for metformin was 43.59 µg/ml and 132.09 µg/ml and for gliclazide 8.96 µg/ml and 27.15µg/ml. According to ICH guidelines, the developed method was validated. Metformin and gliclazide show no interference with the degradation product formed from stress studies. In view of the extended applications of the proposed method for in-vivo drug-drug interaction studies, the method was also studied for elution of few more antidiabetic drugs and also drugs from three other categories possibly co-administered with titled analytes. Drugs from anti-inflammatory, antibacterial, antiviral categories were used to achieve sufficient elution within run time of ten minutes with acceptable system suitability parameters.