No cure exists for multiple sclerosis, though several treatment options exist. Multiple sclerosis patients may take disease-modifying medications, which lower how often they have relapses of the disease and how severe these relapses are. The U.S. Food and Drug Administration has approved eight disease-modifying medications for multiple sclerosis, which include Tysabri (natalizumab), Rebif and Avonex (interferon beta-1a), Betaseron and Extavia (interferon beta-1b), Novantrone (mitoxantrone), Copaxone (glatiramer acetate) and Gilenya (fingolimod). These disease-modifying medications have different methods of delivery. Anonex is an injection done into the muscle, while Extavia, Copaxone, Betaseron and Rebif are injections done under the skin. Patients taking Novantrone and Tysabri receive an IV: Novantrone is administered four times a year, while Tysabri is administered every four weeks, according to the National MS Society's booklet on disease-modifying medication. The last FDA approved disease-modifying medication for multiple sclerosis, Gilenya, is taken orally.