Spectrophotometric determination of lisinopril in three simulated physiological fluids

Abstract

Three simple, accurate and reproducible spectrophotometric methods for the determination of lisinopril in simulated physiological fluids were developed and validated in this study. The methods were based on dissolution of standard lisinopril powder or extraction of the drug from tablet formulation using three dissolution media (0.1 M HCl, phosphate buffer pH 6.8 and phosphate buffer pH 7.4) respectively as solvents. Each resulting extract was filtered and scanned using UV/Vis spectrophotometer (Model SP 3000). The wavelength of maximum absorption (λmax) of lisinopril in 0.1 M HCl, phosphate buffer pH 6.8 and phosphate buffer pH 7.4 were 215 nm, 210 nm and 215 nm respectively. Calibration curves for lisinopril within concentration ranges of 2.5 to 15.0 μg/ml were prepared in each medium. The precisions, accuracy (% relative error), % recoveries, limit of detections and limit of quantitations were respectively determined according to ICH guidelines. The developed methods were then used to assay a sample of standard lisinopril powder and lisinopril tablet; the results were compared with USP method for assay of lisinopril. The developed methods obeyed Beer’s law within the calibration range with correlation coefficients of 0.9974, 0.9978 and 0.9987 respectively. The percentage content of lisinopril in the standard powder and the tablet brand assayed was within the USP range of 98.0 to 102.0 % and 90.0 to 110.0 % respectively. No statistically significant difference was observed between the proposed methods and the USP method (p > 0.05) analyzed with Graph Pad Prism 6 software using Paired Student’s t-test. The proposed methods can be used for quantitative determination of lisinopril in pure form and tablet dosage forms.

Keywords: Lisinopril; Buffers, Assay, Spectrophotometry