Sulthiame-d4 is primarily used in research and development as a labeled compound for analytical studies. It serves as an internal standard in mass spectrometry, aiding in the accurate quantification and detection of sulthiame in biological samples. This application is crucial in pharmacokinetic studies, where understanding the absorption, distribution, metabolism, and excretion of sulthiame is essential. Additionally, it is employed in metabolic pathway investigations to trace the drug's behavior in the body, providing insights into its efficacy and safety. Its deuterated form ensures minimal interference with the analysis, enhancing the precision of experimental results.