infliximab

Infliximab is a TNF-alpha inhibitor, a biologic DMARD (disease-modifying antirheumatic drug) that is a chimeric (part mouse, part human) monoclonal IgG1 antibody. It binds soluble and membrane-bound TNF-alpha, preventing it from interacting with its receptors, thereby inhibiting downstream inflammatory signaling cascades (NF-kB activation, cytokine release, leukocyte recruitment) and inducing apoptosis of TNF-producing cells.

Clinical uses: Crohn's disease (including fistulizing disease), ulcerative colitis, rheumatoid arthritis (usually combined with methotrexate to reduce immunogenicity), ankylosing spondylitis, psoriatic arthritis, and plaque psoriasis.

Key adverse effects and considerations: - Increased risk of infections, particularly reactivation of latent tuberculosis (screen with PPD/IGRA and CXR before starting) and hepatitis B reactivation. - Increased risk of fungal infections (histoplasmosis). - Risk of malignancy, particularly lymphoma (rare, but boxed warning includes hepatosplenic T-cell lymphoma in young patients with IBD, especially when combined with thiopurines). - Infusion reactions and development of anti-drug antibodies (reduced efficacy over time, mitigated by concurrent immunosuppressants like methotrexate or azathioprine). - Can unmask or worsen demyelinating disease (multiple sclerosis-like syndromes) and exacerbate heart failure (contraindicated in moderate-to-severe CHF). - Contraindicated in patients with active serious infections.

Mechanism distinguishes it from other biologics: unlike etanercept (a decoy receptor fusion protein), infliximab and adalimumab are monoclonal antibodies against TNF-alpha directly. Infliximab differs from adalimumab in being chimeric (more immunogenic, requires combination therapy) versus fully humanized.

High-yield boards association: TNF-alpha inhibitors (infliximab, adalimumab, etanercept, certolizumab, golimumab) all carry risk of reactivating latent TB and should prompt screening prior to initiation.