Metamizole-d3 sodium is primarily used in research and analytical applications as an internal standard in mass spectrometry studies. Its deuterated form allows for precise quantification and tracking of metamizole and its metabolites in biological samples, aiding in pharmacokinetic and metabolic studies. This compound is valuable in drug development and toxicology research, enabling accurate measurement of drug concentrations and understanding of its behavior in the body. It is also utilized in clinical studies to ensure reliable data interpretation in therapeutic monitoring and efficacy assessments.