Interferons in multiple sclerosis: ten years' experience.

Interferons (IFNs) were considered for the treatment of patients with multiple sclerosis (MS) after the demonstration, based on small studies, of the efficacy of type IFN beta in decreasing the frequency of exacerbations in relapsing-remitting multiple sclerosis when administered intrathecally, subcutaneously, or intramuscularly. Three preparations of IFN beta are now approved in Europe and North America: chronologically IFN beta-1b (Berlex/Schering), IFN beta-1a given intramuscularly (Biogen), and IFN beta-1a given subcutaneously (Ares Serono). These treatments have now been in use for more than 10 years, and are supposed to decrease relapse rates. However a lot of questions remain unanswered: it is difficult to compare the various preparations; there remain controversies about the effects of different routes of administration and of different dosage preparations; the role of neutralizing antibodies remains partially understood; and the long term effect on disability has not yet been demonstrated.