Finding the Optimum Regimen for Duchenne Muscular Dystrophy

Inclusion Criteria: * Evidence of signed and dated informed consent form. * Confirmed diagnosis of Duchenne muscular dystrophy * Age greater than or equal to 4 years and less than 8 years old * Ability to rise independently from floor, from supine to standing * Willingness and ability to comply with scheduled visits, drug administration plan and study procedures * Ability to maintain reproducible FVC measurements. Exclusion Criteria: * History of major renal or hepatic impairment, immunosuppression or other contraindications to corticosteroid therapy. * History of chronic systemic fungal or viral infections. Acute bacterial infection(including TB) would exclude from enrolment until the infection had been appropriately treated and resolved. * Diabetes mellitus. * Idiopathic hypercalcuria. * Lack of chicken pox immunity and refusal to undergo immunization. * Evidence of symptomatic cardiomyopathy at screening assessment (one to three months prior to the baseline visit). Asymptomatic cardiac abnormality on investigation would not be an exclusion. * Current or previous treatment (greater than four consecutive weeks of oral therapy) with corticosteroids or other immunosuppressive treatments for DMD or other recurrent indications (e.g., asthma), unless approved by FOR-DMD Team (i.e., concurrent participation in another allowed DMD trial). * Inability to take tablets, as assessed by the site investigator by the end of the screening period (the screening period ranges from one to three months prior to the baseline visit). * Allergy/sensitivity to study drugs or their formulations including lactose and/or sucrose intolerance. * Severe behavioral problems, including severe autism. * Previous or ongoing medical condition, medical history, physical findings or laboratory abnormalities that could affect safety, make it unlikely that treatment and follow up will be correctly completed or impair the assessment of study results, in the judgment of the site investigator. * Weight of less than 13 kilograms. * Exposure to any investigational drug currently or within 3 months prior to start of study treatment.