AHU377-d4 (Sacubitril-d4) is primarily used as an internal standard in analytical chemistry for the quantification of sacubitril in biological samples. Its deuterated structure ensures minimal interference with the analyte, providing accurate and reliable results in mass spectrometry-based assays. This application is crucial in pharmacokinetic studies, where precise measurement of sacubitril levels in plasma or other matrices is required to understand drug absorption, distribution, metabolism, and excretion. Additionally, it aids in therapeutic drug monitoring, ensuring optimal dosing and efficacy of sacubitril in clinical settings, particularly in the treatment of heart failure.