Determination of Enantiomeric Impurity in Tegoprazan Drug Substance by HPLC

Tegoprazan is a novel potassium-competitive acid blocker used for gastroesophageal reflux disease. It is administered as the (S)- and (R)-enantiomers are considered impurities that should be controlled. The objective of this work was to establish a chiral analytical method for the determination of the enantiomeric impurity of tegoprazan in the drug substance by high-performance liquid chromatography (HPLC). Enantioselective separation was performed on a Chiralpak alpha1-acid glycoprotein (AGP) column (4.6 mm x 250 mm, 5.0 mu m) at 30 degrees C utilizing a mobile phase consisting of 5 mmol L-1 ammonium acetate buffer (pH 6.0) and 2-propanol (93:7, v/v) at a flow rate of 0.7 mL min-1 with a detection wavelength of 220 nm. The effects of chromatographic conditions, including the type and concentration of organic modifiers, buffer pH, buffer concentration, flow rate, and column temperature, were thoroughly investigated. Under the optimized conditions, the resolution between (S)- and (R)-tegoprazan was greater than 3.0. Moreover, the developed method was validated in terms of linearity, limits of detection (LOD) and quantitation (LOQ), accuracy, precision, and stability. Each enantiomer showed a good linear relationship over the concentration range of 1.0-100 mu g mL-1, with the correlation coefficient of 0.9999. The LOD and LOQ were 0.1 and 0.3 mu g mL-1, respectively. In addition, the recoveries ranged from 94.10% to 99.39% with a relative standard deviation (RSD) of 1.9%. Application of this proposed method to determine the enantiomeric impurity in tegoprazan drug substance proved satisfactory. The quantitative results were about 2.0%, demonstrating that enantiomeric impurity remained in the tegoprazan drug substance and should be controlled in the quality criteria.