Laflunimus suppresses immunoglobulin (Ig) secretion, with IC50 values of 2.5 and 2 μM for IgM and IgG, respectively. Laflunimus also is a prostaglandin endoperoxide H synthase (PGHS) -1 and -2 inhibitor. Laflunimus is an immunosuppressive agent and an analogue of the Leflunomide-active metabolite A77 1726. Laflunimus is an orally active inhibitor of dihydroorotate dehydrogenase (DHODH).

Laflunimus inhibits LPS-induced kappa light-chain cell surface expression on 70Z/3 cells, a property also reversed by uridine. Laflunimus is more potent than A77 1726 as an inhibitor of PGHS in guinea pig polymorphonuclear leukocytes (IC50= 415 and 4400 nM, respectively) and on isolated ovine PGHS-1 (IC50=64 and 742 μM) and PGHS-2 (IC50=100 and 2766 μM).Ig secretion from mouse splenocytes was induced by lipopolysaccharide (LPS) for 5 days.?Laflunimus inhibited the secretion of IgM and IgG with IC50 values of 2.5 and 2 μM , respectively.?Adding Uridine (50 μ M) increased these values to 70 and 60 μ M, respectively.

HR325?inhibits the secondary anti-sheep red blood cell (SRBC) antibody response with ID50 values of 38 mg/kg.