Investigational agents for rheumatoid arthritis.

Agents ranging from simple analgesics to antiinflammatory drugs to powerful immunomodulators have been used for the treatment of rheumatoid arthritis with varying success. Despite the availability of agents that are believed to be "second line" or "disease modifying," many patients either do not respond adequately to available agents or must discontinue their use because of intolerable or dangerous adverse reactions. For this reason, researchers continue to search for more efficacious and less toxic agents for patients with rheumatoid arthritis. This article describes pharmaceutical agents currently under investigation for use in rheumatoid arthritis, including the antiinflammatory agents, zileuton and tenidap, and the immunosuppressive agents, leflunomide, mycophenolic acid (RS-61443), tacrolimus (FK-506), sirolimus (rapamycin), amiprilose (therafectin), cladribine (2- chlorodeoxyadenosine), and azaribine.