Actarit (MS-932) is an anti-inflammatory drug developed in Japan for use in rheumatoid arthritis (RA). Actarit suppresses adjuvant arthritis through modulation of the immune system. Actarit acts on RA synovial cells to reduce cell-cell interactions with autologous synovium infiltrating lymphocytes and to inhibit proinflammatory cytokine and MMP production, leading to amelioration of symptoms of RA.