In vitro assessment of the biologic activity of interferon beta formulations used for the treatment of relapsing multiple sclerosis.

A new formulation (NF) of subcutaneous (sc) interferon (IFN) β-1a was developed in an attempt to improve injection tolerability and immunogenicity. We compared antiviral and IFNβ-stimulated gene (ISG) activities of IFNβ-1a sc NF with IFNβ-1a sc original formulation and IFNβ-1b sc. When equivalent unit amounts were compared, the IFNβ formulations demonstrated similar antiviral activity and induced similar levels of ISG mRNA. However, on a weight basis (ng/mL), significantly more IFNβ-1b sc was needed to equal the antiviral activity of either IFNβ-1a sc formulation, and both IFNβ-1a sc formulations induced significantly higher levels of ISG mRNA than IFNβ-1b sc.