During the study, there will be 6 visits in the Hospital over a maximum of 10 weeks. At each visit, patients will undergo safety examinations including vital signs, physical and neurological examinations, ECG, safety and hematology, biochemistry and urinalysis, concomitant treatments review, and any symptoms and side effects review. In addition, blood samples will be withdrawn for the evaluation of Rimeporide in plasma. Finally, additional blood & urine samples will be collected to explore efficacy markers. Patients will also undergo 2 NMR (at screening and End of study) to develop non invasive biomarkers for further investigations in DMD patients.