STABILITY INDICATING METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF SITAGLIPTIN PHOSPHATE AND METFORMIN HCl IN TABLETS BY HPLC

An accurate, simple, new, precise, rugged and stability indicating method was developed for simultaneous estimation of sitagliptin and metformin HCl in tablets. The developed method was rapid and economic. The Chromatographic separation was achieved isocratically on a C-18 column by using ammonium acetate buffer (adjusted to pH 5.0 with glacial acetic acid): MeOH (60:40 v/v). Octane -1-sulfonic acid sodium salt was used as an ion pair agent. Flow rate of 1mL/min with dual wavelength UV detection (265nm for sitagliptin & 225 nm for metformin) was used. The retention times of metformin and sitagliptin are 2.398 min and 17.113min respectively. The developed method was specific and well separated from the impurities of both sitagliptin and metformin. The method is linear in a range of 50% to 150% for both sitaglitpin and metformin. The correlation coefficient was found to be r²= 0.9997 & 0.9998 for sitagliptin and metformin respectively. Both standard and test solutions proved to be stable for up to 48 h. Forced degradation study showed that the method is stability indicating. The developed method can be used for routine analysis of sitaglitpin and metformin fixed dose combination.