A liquid chromatographic method for separation of sacubitril-valsartan and their stereoisomeric impurities

Sacubitril-valsartan (SV) is a first-in-class inhibitor of the angiotensin II receptor and neprilysin for the treatment of chronic heart failure (HF) and hypertension. A stereoselective normal-phase high performance liquid chromatographic method was developed and validated for separation of sacubitril (SA), valsartan (VA) and their stereoisomeric impurities. Chromatography was performed using mobile phase A of n-hexane with 0.1% TFA added and mobile phase B comprising ethanol, isopropanol and TFA (80:20:0.1, v/v/v) and delivered at a flow rate of 1.0 mL min(-1) on a Chiralcel OJ-H column (250 mm x 4.6 mm, 5 m). The stereoisomers were monitored at a wavelength of 254 nm and the whole separation was achieved within 50 min. The method was validated in terms of specificity, linearity (R-2 0.998), accuracy (98.3-99.5%), precision (%RSD 1.82), limit of detection (0.06 g mL(-1) and 0.10 g mL(-1)) and limit of quantification (0.2 g mL(-1) and 0.3 g mL(-1)). The sample solution and mobile phase were found to be stable for at least 48 hours. The final optimized method was successfully applied to separate sacubitril-valsartan from their stereoisomers and showed characteristics of good repeatability and accuracy for quantitative determination of the stereoisomers in bulk drug.