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