Teriflunomide-d4 is the deuterium labelled form of Teriflunomide.
Teriflunomide-d4 is the stable deuterium-labeled form of Teriflunomide (Aubagio), the active metabolite of leflunomide. It is used as an internal standard in LC-MS/MS for quantitating teriflunomide in biological samples in clinical and diagnostic testing, including therapeutic drug monitoring assays. Targets: Dihydroorotate Dehydrogenase (DHODH), Isotope-Labeled Compounds. Teriflunomide inhibits DHODH, a key mitochondrial enzyme in de novo pyrimidine synthesis, thereby suppressing T and B lymphocyte proliferation. The deuterated form is an analytical standard. The non-labeled form inhibits DHODH with IC50 values in the low nanomolar range and significantly reduces lymphocyte proliferation in mixed lymphocyte reaction assays. As an internal standard, no direct in vitro activity is reported. In vivo, teriflunomide is orally active and has demonstrated efficacy in reducing disease severity in animal models of multiple sclerosis (EAE model) and rheumatoid arthritis (collagen-induced arthritis). For cell-free assays, a typical protocol: thaw plasma or serum samples, add Teriflunomide-d4 internal standard, perform protein precipitation with acetonitrile, centrifuge, evaporate supernatant, reconstitute, and inject into LC-MS/MS system for quantitation. No specific cell-based assays are performed with the deuterated internal standard; however, parent teriflunomide is tested in human peripheral blood mononuclear cell (PBMC) proliferation assays stimulated with mitogens or alloantigens. Animal studies for the deuterated standard are not applicable; it is used in bioanalysis after dosing animals with unlabeled drug. For teriflunomide, typical in vivo PK studies involve oral administration to rats or dogs, followed by serial blood collection and LC-MS/MS analysis using the d4 internal standard. PK properties of teriflunomide: plasma protein binding >99%, long elimination half-life (approximately 2 weeks in humans), extensive enterohepatic circulation, and slow clearance. The deuterated standard itself does not exhibit distinct PK behavior. Non-labeled teriflunomide has a favorable safety profile; common adverse effects include alopecia, diarrhea, influenza, nausea, and elevated liver enzymes. It carries a boxed warning for hepatotoxicity and teratogenicity. The deuterated standard is non-toxic as used. Teriflunomide is FDA-approved for relapsing-remitting multiple sclerosis. It is also the active metabolite of leflunomide, approved for rheumatoid arthritis. The deuterated standard is for research use only and not for human administration. It is a certified reference material (Cerilliant).

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.