I am a MS training nurse, I train on all of the injectable and most of the IV drugs.
Rebif, Avonex,
Copaxone, Betaserone and Extavia are all first line of defense drugs. Rebif and Extavia and Avonex are the same drug. Avonex is the smallest dose but the biggest needle. Extavia is a larger dose than Rebif, simply because it is every other day, as Rebif is 3x a week. Copaxone is the most compatable with your natural body and has the least side effects, but is a daily injection .