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A novel ultra‐performance liquid chromatographic (UPLC) method has been developed and approved for the quantitative determination of enzalutamide (ENZ) and its impurities in drug product dosage form by applying the quality by design with design of experiments approach. An efficient chromatographic separation was achieved on a Waters ACQUITY CSH C18 (100 × 2.1 mm × 1.7 μm) column in gradient elution mode. A mixture of potassium phosphate monobasic buffer and acetonitrile (10 mm, adjusted to pH 4.0 with 1% orthophosphoric acid) at a flow rate of 0.2 mL min−1 (column temperature at 40°C) under ultraviolet detection at 270 nm was used for quantitation. The peak resolution among ENZ and its impurities (Impurity‐1, Impurity‐2, Impurity‐3, Impurity‐4, Impurity‐5, Impurity‐6 and Impurity‐7) was greater than 2.5. Regression analysis confers an R2 value (correlation coefficient) higher than 0.999 for the active substance and impurities. The detection level for ENZ impurities was at a level below 0.015% (0.12 μg/mL). The accuracy levels for different compounds were close to 100%. The inter‐ and intra‐day precisions for ENZ and impurities were evaluated and their relative standard deviation (%) values were less than 3.5. Our results show that the UPLC–UV stability‐indicating method will be an essential tool that could determine the drug product’s impurities and be useful in regular quality control and stability studies of the ENZ drug product dosage form.

A simple and isocratic reverse-phase liquid chromatography with mass spectrometric method has been developed and validated for the determination of heptaethylene glycol monomethyl ether in benzonatate drug substance. Benzonatate is an oral antitussive drug used to relieve and suppress cough in patients older than 10 years.The presence of residual heptaethylene glycol monomethyl ether in the benzonatate drug substance affects the safety, strength, purity and quality of the drug substance.The subject compound separation was achieved using 0.1% formic acid and acetonitrile (50:50 v/v) at a flow rate of 0.3 ml/min. The Suplex PKB-100 250 × 4.6 mm, 5 μm LC column was used for a better peak shape. Detection was carried out at an m/z value of 341. The linearity curve showed a correlation of coefficient of >0.999.The precision and intermediate precision (RSD) were <7.30. The accuracy values were >90% for all levels. The developed method was validated as per International Conference on Harmonization guidelines and found to be a novel, specific and sensitive analytical method for determination of components of interest.