Safety and tolerability of a 'refrigeration-free' formulation of interferon beta-1b--results of a double-blind, multicentre, comparative study in patients with relapsing-remitting or secondary progressive multiple sclerosis.

The original glucose-based formulation of Betaferon/Betaseron (interferon beta-1b) requires refrigerated storage. A refrigeration-free formulation of interferon beta-1b, based on mannitol, is stable at room temperature for up to 2 years, and offers a greater degree of flexibility for patients with multiple sclerosis (MS). We compared the safety and tolerability of the two formulations in a 24-week, randomized, double-blind, parallel group, Phase IV clinical study conducted in 303 patients with MS. Patients received the glucose formulation (IFNbeta-1b-G) for 8 weeks, and were then randomized to receive either IFNbeta-1b-G or the refrigeration-free formulation (IFNbeta-1b-M) for a further 8 weeks. On completion of the double-blind phase, all patients received IFNbeta-1b-M for an 8-week follow-up period. The primary outcome measure was the proportion of injection sites that developed reactions per patient during the double-blind period. In addition, a range of secondary outcomes relating to these reactions was also assessed. The difference in the proportion of injection-site reactions between the two groups was not statistically significant (59% IFNbeta-1b-G versus 60% IFNbeta-1b-M). There were no statistically significant differences observed between the two treatment groups in any of the secondary tolerability endpoints. The results from this study demonstrate that the tolerability and safety profiles of both formulations are extremely good, and that the refrigeration-free formulation of interferon beta-1b is comparable with that of the original glucose formulation.