Leflunomide

Leflunomide is a synthetic isoxazol and a prodrug form of A-771726 (Item No. 14404), a dihydroorotate dehydrogenase inhibitor.¹ Leflunomide inhibits de novo pyrimidine synthesis to regulate T lymphocyte progression through the cell cycle. It inhibits proliferation and activation of T cells when used at concentrations of 25 and 100 µM, respectively, for naïve and memory CD4⁺ T cells.² It also reduces the production of Th1 effector cells and increases differentiation of Th2 cells in vitro and in splenocytes isolated from KLH-immunized mice. Leflunomide (35 mg/kg per day) reduces and prevents inflammation in a proteoglycan-induced mouse model of rheumatoid arthritis.³ Formulations containing leflunomide have been used in the treatment of active rheumatoid arthritis.

WARNING This product is not for human or veterinary use.

1. Breedveld, F.C., and Dayer, J.-M. Leflunomide: Mode of action in the treatment of rheumatoid arthritis. Ann. Rheum. Dis. 59(11), 841-849 (2000).

2. Dimitrova, P., Skapenko, A., Herrmann, M.L., et al. Restriction of de novo pyrimidine biosynthesis inhibits Th1 cell activation and promotes Th2 cell differentiation. J. Immunol. 169(6), 3392-3399 (2002).

3. Glant, T.T., Mikecz, K., Bartlett, R.R., et al. Immunomodulation of proteoglycan-induced progressive polyarthritis by leflunomide. Immunopharmacology 23(2), 105-116 (1992).