Used as an internal standard in mass spectrometry-based bioanalytical assays for the quantification of vildagliptin in biological samples. Its primary application is in pharmacokinetic and metabolic studies, where it helps ensure accurate measurement of vildagliptin concentrations by compensating for matrix effects and instrument variability. Due to the deuterium-labeled structure, it closely mimics the behavior of the unlabeled compound during sample processing and analysis, making it ideal for use in drug development and clinical research.