Anakinra, a recombinant human interleukin-1 (IL-1) receptor antagonist, is the 
first biological agent approved to block the pro-inflammatory effects of IL-1 in 
patients with rheumatoid arthritis. In a double-blind, randomised trial in 472 
patients with active, severe or very severe rheumatoid arthritis, recipients of 
subcutaneous anakinra 150 mg/day achieved higher response rates [assessed using 
the American College of Rheumatology (ACR) composite score] and accumulated more 
mean productivity days after 6 months than placebo recipients. However, the 
response rates and accumulated productivity days of patients receiving 
subcutaneous anakinra 30 or 75 mg/day for 6 months were similar to those of 
placebo. With respect to the total Genant radiographic scores, the same study 
showed that all anakinra treatment regimens slowed disease progression after 6 
months to a greater extent than placebo. In double-blind, randomised trials in 
patients with rheumatoid arthritis, combined treatment with anakinra and 
methotrexate was associated with higher ACR 20, 50 and 70 response rates than 
with methotrexate alone. Anakinra, used alone or in combination with 
methotrexate, was generally well tolerated, with the most frequent adverse event 
being a mild injection-site reaction of transient duration. Infections requiring 
antibacterial therapy or hospitalisation occurred more commonly in anakinra 
recipients than in placebo recipients, but were a rare cause for discontinuation 
of anakinra therapy (approximately 1%) in clinical trials.