etanercept

Etanercept is a biologic disease-modifying antirheumatic drug (DMARD) that inhibits tumor necrosis factor (TNF). It is a fusion protein consisting of two soluble TNF receptor domains fused to the Fc portion of human IgG1. By acting as a decoy receptor, etanercept binds TNF-α (and lymphotoxin-α) and prevents TNF from interacting with cell-surface TNF receptors, reducing inflammatory signaling.

Etanercept is approved for multiple autoimmune conditions, including rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, juvenile idiopathic arthritis, and plaque psoriasis. It may be used alone or with other DMARDs such as methotrexate, depending on the disease.

Administration is by subcutaneous injection, usually given twice weekly at a dose of 25 mg or at 50 mg once weekly for adults with RA; dosing varies by condition and body weight in pediatric patients. The drug is typically self-administered after appropriate instruction.

Safety: Etanercept can increase the risk of serious infections, including reactivation of latent tuberculosis; TB testing and hepatitis screening are recommended before starting therapy. Other risks include injection-site reactions, headaches, and rare demyelinating disorders or heart failure exacerbation. Immunogenicity is possible, with patients sometimes developing anti-drug antibodies that may reduce efficacy. Live vaccines are generally contraindicated during treatment; vaccination decisions should be individualized.

Notes: Etanercept was among the first TNF inhibitors approved for autoimmune diseases (brand name Enbrel). The drug is produced by recombinant DNA technology and is administered by subcutaneous injection.