Osimertinib-d6 is primarily used in research and development as an internal standard in analytical chemistry, particularly in mass spectrometry. Its deuterated form ensures accurate quantification and identification of the parent compound, osimertinib, in biological samples. This application is crucial in pharmacokinetic studies, where precise measurement of drug concentrations in plasma or tissues is required to understand absorption, distribution, metabolism, and excretion. Additionally, it aids in the validation of analytical methods, ensuring reliability and reproducibility in clinical and preclinical studies focused on cancer treatment, specifically for non-small cell lung cancer (NSCLC). Its use enhances the precision of drug monitoring and supports the development of targeted therapies.