This study will help to determine the safety and efficacy of the mast cell stabilizer Oxatomide as a treatment for Duchenne muscular dystrophy (DMD). Boys with DMD who are enrolled in this study will should not have taken steroids to treat DMD for at least twelve months, and should not have taken any nutritional supplements for at least three months. Subjects will complete a two screening visits within a one-week period, and if enrolled will then have their strength tested monthly for three months before beginning therapy with Oxatomide. Once Oxatomide therapy is started, participants will have their strength tested monthly for six months. Following the six month treatment period, participants will be given the option to remain on Oxatomide until the study is completed.