Abstract

METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF SIMVASTATIN AND SITAGLIPTIN BY RP-HPLC IN BULK AND PHARMACEUTICAL FORMULATIONS

Syed Jahid, K. Thejomoorthy* and Ch Saibabu

ABSTRACT

Simple accurate and precise Spectrophotometric methods have been developed for simultaneous estimation of Simvastatin (SIM) and Sitagliptin (SITA) by employing six methods (four UV, one RP-HPLC and one Colorimetry). The Four UV Methods were Method A was simultaneous equation method; the method involves formation and solving the simultaneous equation using 238 nm and 267 nm as two wavelengths for SIM and SITA respectively. Method B was first order derivative spectrophotometry. The first order derivative absorption at 230 nm (zero crossing point of SITA) was used for SIM and 275nm (zero crossing point of SIM) was used for SITA. Method C involved Q-absorption analysis based on the measurement of absorbance at twowave lengths that is the λmax of SITA 267 nm and iso-absorptive point of both drugs at 250 nm. Method D is based on dual wavelength analysis; two wavelengths were selected for each drug in such a way that the difference in absorbance was zero for the second drug. At wavelengths 225 and 248 nm SITA had equal absorbance values; therefore, these two wavelengths have been used to determine SIM; on a similar basis 254 and 274 nm were selected to determine SITA in their binary mixtures. The four methods obeyed the Beer’s law in the concentration range of 3-15 μg/ml for SIM and 50-150 μg/ml for SITA. A simple and rapid gradient reversed-phase high- performance liquid chromatographic method (RP-HPLC) have been developed and validate for the simultaneous estimation of SIM and SITA in combined dosage form. The chromatographic separation was achieved by using mobile phase Water: Methanol: Acetonitrile (20:30:50), a C-18 column. The mobile phase was pumped at a flow rate of 1 mL/min and the eluents were monitered at 250 nm. Retention times were 3.407 min and 4.320 min for SITA and SIM respectively. Linearity for SIM and SITA was established in the range of 2-10μg/ml and 20-60 μg/ml /mL, respectively. The selectivity and sensitivity of the visible spectrophotometric method depends only on the nature of chemical reaction involved in the colour development. The chromogenic agents used were 3-methyl-2-benzothiazolinone hydrazone (MBTH), reacts with drug in the presence of ferric chloride gives intense green colour and measure the absorbance against reagent blank, shows the maximum absorbance at 621 nm for SIM and 664 nm for SITA. Method, involves the measurement of absorbances at two wavelengths, the drugs obey Beer’s Lambert’s law in the concentration range of 25–125 μg/mL for SIM and 50-150 μg/ml for SITA respectively. All the six methods were validated in terms of accuracy, precision, linearity, range, and specificity, limit of detection and limit of quantitation in accordance with ICH guidelines. The results show all these methods were found to be efficient, accurate, precise, specific and economic and are suitable for routine quality control analyses.

Keywords: ICH, HPLC, Validation, Simvastatin, Sitagliptin.