Derivative spectrophotometric method for simultaneous determination of ezetimibe and simvastatin in combined tablets

The introduced study portrays the development and validation of an effortless, speedy and selective first order derivative zero-crossing spectrophotometric method to estimate ezetimibe and simvastatin simultaneously in combined drug products over and above in the presence of ezetimibe alkaline degradation products. Ezetimibe and its alkaline degradates spectra showed zero-crossing point at 249 nm, so the amplitude at 249 nm could be used for calculating the concentration of simvastatin. While simvastatin and ezetimibe alkaline degradates spectra showed a zero-reading value at 261 nm, so ezetimibe could be determined by measuring the amplitude at 261 nm. Regression plots revealed good linear relationships in the concentration range 1-16 μg/mL with accuracy checked by conducting recovery studies; average recovery was 99.61 ± 1.183 and 100.47 ± 1.310 for ezetimibe and simvastatin, respectively. The suggested first derivative spectrophotometric method was successfully applied for the determination of the cited drugs in "Inegy 10/10, 10/20 and 10/40 tablets". Satisfactory results were obtained for the recovery of both drugs and were in good agreement with the labeled amounts. Method validation was estimated according to USP guidelines.