Swiss drug maker Novartis AG says it has received European Union approval to sell its oral multiple sclerosis medication Gilenya in the 27-nation bloc, according to the Associated Press. The Basel-based company says studies show a 0.5 milligram daily dose significantly reduces the risk of disability progression in some patients with relapsing-remitting multiple sclerosis. The drug works by preventing the immune system from damaging the body''s own nervous system. The U.S. Food and Drug Administration approved Gilenya to reduce relapses in patients with MS last September. Potential sales of Gilenya could reach $2 billion by 2015.