5-[1-[3,3-diphenylpropyl(methyl)amino]-2-methylpropan-2-yl]oxycarbonyl-2,6-dimethyl-4-(3-nitrophenyl)pyridine-3-carboxylic acid

This compound is a structurally modified derivative of diphenhydramine, designed as a reference standard for pharmaceutical impurity profiling. It is used in analytical testing to ensure the quality and purity of diphenhydramine-containing drug products.