rac CP-690550 Citrate-13C3-15N, also known as rac-Tofacitinib 13C3-15N Citrate, is an isotopically labeled form of the drug tofacitinib, a Janus kinase (JAK) inhibitor used to treat autoimmune diseases such as rheumatoid arthritis. In this compound, three carbon atoms are replaced with the carbon-13 isotope, and one nitrogen atom is replaced with the nitrogen-15 isotope. The citrate salt form improves solubility and stability. This isotopic labeling is particularly useful in pharmacokinetic and metabolic studies, allowing for precise tracking and analysis using NMR spectroscopy and mass spectrometry. Despite the isotopic substitution, it retains the same pharmacological properties as the non-labeled drug, making it valuable for research into its mechanism of action and metabolic pathways.
