Used as a stable isotope-labeled internal standard in mass spectrometry-based bioanalytical assays for quantifying ipronidazole and its metabolites in biological samples. Its primary application is in pharmacokinetic and metabolic studies, where it helps ensure accurate measurement by compensating for matrix effects and instrument variability. Due to its deuterated structure, it closely mimics the behavior of the non-labeled compound while being distinguishable by mass detection, making it ideal for drug development and toxicology research.