Anakinra

Anakinra is a biologic DMARD that is a recombinant, non-glycosylated form of the human IL-1 receptor antagonist. It works by competitively inhibiting the binding of IL-1α and IL-1β to the interleukin-1 type I receptor (IL-1RI), thereby blocking IL-1-mediated inflammatory signaling, which includes downstream NF-κB activation and production of inflammatory mediators (e.g., PGE2, COX-2, iNOS).

Clinical uses: - Rheumatoid arthritis (less commonly used now due to availability of more effective biologics like TNF inhibitors) - Cryopyrin-associated periodic syndromes (CAPS), including familial cold autoinflammatory syndrome, Muckle-Wells syndrome, neonatal-onset multisystem inflammatory disease (NOMID) - Off-label: Systemic juvenile idiopathic arthritis, adult-onset Still's disease, gout flares, COVID-19 (investigational), macrophage activation syndrome

Pharmacokinetics: Short half-life (~4-6 hours), requires daily subcutaneous injection (unlike longer-acting biologics such as canakinumab, an anti-IL-1β monoclonal antibody given less frequently).

Adverse effects: - Injection site reactions (most common) - Increased risk of infections (live vaccines contraindicated) - Neutropenia - Headache - Should not be combined with TNF inhibitors (increased infection risk without added efficacy)

Mechanistic distinction from other IL-1 pathway drugs: - Anakinra: IL-1 receptor antagonist (blocks both IL-1α and IL-1β) - Canakinumab: Monoclonal antibody against IL-1β specifically - Rilonacept: IL-1 trap (soluble decoy receptor)

High-yield boards point: Anakinra is a classic example of a cytokine receptor antagonist biologic, important to distinguish from monoclonal antibody biologics (e.g., infliximab, adalimumab) in pharmacology questions. Mechanism relates to IL-1 physiology: IL-1 is a key pyrogen and mediator of innate immune inflammatory responses, produced by macrophages/monocytes, and plays a central role in autoinflammatory syndromes caused by NLRP3 inflammasome dysregulation.