Safety of anakinra, a recombinant interleukin-1 receptor antagonist (r-metHuIL-1ra), in patients with rheumatoid arthritis and comparison to anti-TNF-alpha agents.

Anakinra is a recombinant human interleukin-1 receptor antagonist (IL-1ra) recently approved by the FDA as a new therapy for patients with rheumatoid arthritis. Four clinical trials have been completed which have demonstrated that anakinra is an effective anti-rheumatic therapy either used alone or in combination with methotrexate. The most frequent adverse events reported in the clinical trials are injection-site reactions which are generally mild to moderate and rapidly resolve. A large, prospective safety study which allowed a wide-variety of comorbid conditions and concomitant medications demonstrated that anakinra therapy is a well-tolerated treatment for rheumatoid arthritis in the patient population seen by the practicing rheumatologist. Unlike therapies designed to affect TNF-alpha, there have not yet been reports of the development of tuberculosis or other fungal infections, demylinating syndromes or worsening of congestive heart failure. The safety profile of etanercept and infliximab were similar to that of anakinra in the phase I-phase III clinical trials. Unlike anakinra, these medications were not studied in the usual rheumatoid arthritis population which includes a number of patients with a wide variety of co-morbid disease and utilizing a number of concomitant anti-rheumatic medications. Post approval, several safety concerns, including patients at risk for serious infection and the emergence of latent tuberculosis and other opportunistic infections have emerged with the use of anti TNF therapy.