Sunitinib-d10, a deuterated form of sunitinib, is primarily used in research and development as an internal standard in mass spectrometry-based assays. Its application is crucial for the accurate quantification of sunitinib in biological samples, such as plasma or tissue, during pharmacokinetic and pharmacodynamic studies. The incorporation of deuterium atoms enhances its stability and allows for precise differentiation from the non-deuterated compound, ensuring reliable analytical results. This compound is particularly valuable in drug development and clinical research, where understanding the absorption, distribution, metabolism, and excretion of sunitinib is essential. Additionally, it aids in the validation of analytical methods, contributing to the optimization of therapeutic strategies for diseases like renal cell carcinoma and gastrointestinal stromal tumors.