Drug Information for ENBREL (etanercept) For Subcutaneous Injection (Immunex Corp): DESCRIPTION

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 C_H2 domain, the C_H3 domain and hinge region, but not the C_H1 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^® single-use prefilled syringes are available in 25 mg (0.51 mL of a 50 mg/mL solution of etanercept) and 50 mg (0.98 mL of a 50 mg/mL solution of etanercept) dosage strengths.

ENBREL^® single-use prefilled SureClick^® autoinjectors are available in 50 mg (0.98 mL of a 50 mg/mL solution of etanercept).

The solution of ENBREL^® is clear and colorless, sterile, preservative-free, and is formulated at pH 6.3 ± 0.2. Each ENBREL^® prefilled syringe and SureClick autoinjector contains a 50 mg/mL solution of etanercept with 1% sucrose, 100 mM sodium chloride, 25mM L-arginine hydrochloride, and 25mM sodium phosphate.

ENBREL^® multiple-use vials are available containing 25 mg of etanercept. ENBREL^® is supplied in a multiple-use vial as a 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.

Administration of one 50 mg ENBREL^® prefilled syringe or one ENBREL^® SureClick autoinjector provides a dose equivalent to two 25 mg ENBREL^® prefilled syringes or two multiple-use vials of lyophilized ENBREL^®, when vials are reconstituted and administered as recommended.