SPL Set ID: d70a39cc-de15-4c12-a1ec-8063b69ea0e1

Interferon beta-1a, an interferon beta, is a 166 amino acid glycoprotein with a molecular weight of approximately 22,500 daltons. It is produced by recombinant DNA technology using genetically engineered Chinese Hamster Ovary cells into which the human interferon beta gene has been introduced. The amino acid sequence of AVONEX is identical to that of natural human interferon beta. Using the World Health Organization (WHO) International Standard for Interferon, AVONEX has a specific activity of approximately 200 million international units of antiviral activity per mg of interferon beta-1a determined specifically by an in vitro cytopathic effect bioassay using lung carcinoma cells (A549) and Encephalomyocarditis virus (ECM). AVONEX 30 micrograms contains approximately 6 million international units of antiviral activity using this method. The activity against other standards is not known. Comparison of the activity of AVONEX with other interferon betas is not appropriate, because of differences in the reference standards and assays used to measure activity. AVONEX (interferon beta-1a) injection is a sterile liquid for intramuscular injection available in a prefilled glass syringe or a prefilled glass syringe surrounded by an autoinjector. Each single-dose prefilled glass syringe or single-dose prefilled autoinjector delivers 0.5 mL of solution containing 30 micrograms of interferon beta-1a, arginine hydrochloride, USP (15.8 mg), glacial acetic acid, USP (0.25 mg), polysorbate 20 (0.025 mg), sodium acetate trihydrate, USP (0.79 mg), and Water for Injection, USP at a pH of approximately 4.8.