Anakinra

• Rheumatoid Arthritis
• Neonatal-Onset Multisystem Inflammatory Disease (NOMID)
• Adult-Onset Still's Disease
• Recurrent Pericarditis

Anakinra is a recombinant interleukin-1 receptor antagonist (IL-1Ra) used in the treatment of rheumatoid arthritis and other autoinflammatory conditions. This biologic medication works by blocking the inflammatory effects of interleukin-1, a key cytokine in the pathogenesis of various inflammatory diseases.

Mechanism of Action

Anakinra is a recombinant form of the naturally occurring human interleukin-1 receptor antagonist (IL-1Ra). It competitively binds to the interleukin-1 type I receptor (IL-1RI), blocking the binding of both IL-1 alpha and IL-1 beta. IL-1 is a pro-inflammatory cytokine that plays a central role in cartilage degradation, bone resorption, and synovial inflammation in rheumatoid arthritis. By blocking IL-1 signaling, anakinra reduces inflammation, prevents joint damage, and improves symptoms. The mechanism is also effective in autoinflammatory conditions characterized by excessive IL-1 production.

Available Formulations

Anakinra is available as a solution for subcutaneous injection in prefilled syringes containing 100 mg/0.67 mL. The medication requires refrigeration and should be protected from light. Each syringe is intended for single use only. Patients can self-administer injections after proper training.

Medical Uses

Anakinra is FDA-approved for reducing signs and symptoms of moderately to severely active rheumatoid arthritis in adults who have failed one or more disease-modifying antirheumatic drugs (DMARDs). It is also approved for neonatal-onset multisystem inflammatory disease (NOMID), a severe autoinflammatory condition. Off-label uses include other autoinflammatory diseases such as familial Mediterranean fever, adult-onset Still's disease, recurrent pericarditis, and gout flares refractory to standard therapy.

Dosing Guidelines

For rheumatoid arthritis, the recommended dose is 100 mg administered subcutaneously once daily. For NOMID, dosing starts at 1-2 mg/kg/day and can be increased based on response. Injections should be given at approximately the same time each day and can be self-administered into the thigh, upper arm, or abdomen. Injection sites should be rotated. Patients with severe renal impairment (CrCl less than 30 mL/min) or end-stage renal disease should receive the dose every other day.

Important Safety Information

Anakinra should not be initiated in patients with active infections. Patients should be monitored for signs of infection during treatment, and the medication should be discontinued if a serious infection develops. The combination of anakinra with TNF-blocking agents is associated with an increased risk of serious infections and neutropenia and is not recommended. Live vaccines should not be administered during treatment. Injection site reactions are common but usually mild.

Drug Interactions

Concurrent use with TNF-blocking agents (etanercept, infliximab, adalimumab) significantly increases the risk of serious infections and is not recommended. Anakinra may be used with non-biologic DMARDs including methotrexate. No formal drug interaction studies have been conducted, but the medication is not metabolized by cytochrome P450 enzymes and is unlikely to have pharmacokinetic interactions.

Special Populations

There are limited data on anakinra use during pregnancy; use only if clearly needed. It is unknown whether anakinra is excreted in human breast milk; caution should be exercised. Safety and efficacy have been established in pediatric patients with NOMID. Elderly patients may be more susceptible to infections. Dose adjustment is required for severe renal impairment (every other day dosing). Patients should be screened for latent tuberculosis before starting therapy.