Dose and Frequency of Administration of Interferon-beta Affect its Efficacy in Multiple Sclerosis.

Data reviewed in this article demonstrate that both interferon-beta-1a (IFNbeta-1a) and interferon-beta-1b (IFNbeta-1b) show a dose-response relationship in multiple sclerosis at current clinical doses. Moreover, the efficacy of these therapies is probably dependent on their frequent administration to maintain optimal levels of biological effect. These results differ from the conclusions of a recent review of data comparing two doses of IFNbeta-1a, given intramuscularly once weekly, that showed no difference in efficacy between the two doses. This and other results were interpreted to indicate that the current dose of this product (30microg intramuscularly once weekly) is optimal. However, the data reviewed here indicate that the efficacy of IFNbeta differs depending on the features of the dose regimen, including total dose, route and frequency of administration. Direct comparative data indicate that 44microg given subcutaneously three times weekly is more effective on clinical and magnetic resonance imaging measures, at least up to 48 weeks of therapy, compared with 30microg intramuscularly once weekly; risk-benefit favours 44mug three times weekly over 30mug once weekly.