In treating multiple sclerosis with beta interferon-1a, both dose and frequency of administration are important.

The standard dose of intramuscular (IM) beta interferon-1a may be too low for some patients and switching to a higher dose preparation of beta interferon-1a could ameliorate breakthrough disease activity.

In the past, currently available higher dose formulations of beta interferon-1a required switching to subcutaneous administration which is concerning for higher incidence of cutaneous side effects and neutralizing antibodies.

Our retrospective non-randomized, clinical data analysis provides limited evidence that increasing the frequency of IM beta interferon-1a to twice a week can ameliorate breakthrough disease activity in some cases. While we do not encourage the off-label use of higher doses of the standard preparation of IM beta interferon-1a, the recently FDA-approved IM preparation of peginterferon beta-1a, which gives a higher dose of beta interferon-1a over a 2-week period than weekly IM beta interferon-1a, would then be a commercially available option.