ENBREL® (etanercept) is a dimeric fusion protein consisting of the extracellular ligand-binding portion of the human 75 kilodalton (p75) tumor necrosis factor receptor (TNFR) linked to the Fc portion of human IgG1. The Fc component of etanercept contains the CH2 domain, the CH3 domain and hinge region, but not the CH1 domain of IgG1. Etanercept is produced by recombinant DNA technology in a Chinese hamster ovary (CHO) mammalian cell expression system. It consists of 934 amino acids and has an apparent molecular weight of approximately 150 kilodaltons.
ENBREL® is supplied in a single-use prefilled 1 mL syringe as a sterile, preservative-free solution for subcutaneous injection. The solution of ENBREL® is clear and colorless and is formulated at pH 6.3 ± 0.2. Each ENBREL® single-use prefilled syringe contains 0.98 mL of a 50 mg/mL solution of etanercept with 10 mg/mL sucrose, 5.8 mg/mL sodium chloride, 5.3 mg/mL L-arginine hydrochloride, 2.6 mg/mL sodium phosphate, monobasic, monohydrate, and 0.9 mg/mL sodium phosphate, dibasic, anhydrous. Administration of one 50 mg/mL prefilled syringe of ENBREL® provides a dose equivalent to two 25 mg vials of lyophilized ENBREL®, when vials are reconstituted and administered as recommended.
ENBREL® multiple-use vial contains sterile, white, preservative-free, lyophilized powder. Reconstitution with 1 mL of the supplied Sterile Bacteriostatic Water for Injection (BWFI), USP (containing 0.9% benzyl alcohol) yields a multiple-use, clear, and colorless solution with a pH of 7.4 ± 0.3 containing 25 mg etanercept, 40 mg mannitol, 10 mg sucrose, and 1.2 mg tromethamine.