▴ 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 (≈1%) in clinical trials.Table.Features and properties of anakinra (recombinant human interleukin-1 receptor antagonist, rhIL-1ra)Figure. Anakinra