Inclusion Criteria:  Participants who have completed Study EDG-5506-001.  Participants who were not from Study EDG-5506-001 must meet the following:  Male sex at birth and aged 18 to 55 years inclusive at time of consent. Documented dystrophin mutation with phenotype consistent with BMD. Ambulatory at Screening (defined as ability to complete 100 meter [m] timed test, with or without assistance). Body weight ≥ 50 kg at the Screening visit. Body mass index (BMI) between 20 and 34 kg/m2 inclusive.  Exclusion Criteria:  Receipt of oral corticosteroids for >5 days in the previous 6 months at a dose of >5 mg equivalent per day. Lower oral doses or inhaled/intranasal steroids are permitted. Receiving moderate or strong cytochrome P450 CYP3A4 inhibitors or inducers. Participation in any other investigational drug study or use of use of an investigational drug within 30 days or 5 half-lives (whichever is longer) of dosing in the present study. Medical history or other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory result or abnormality that may increase the risk of study participation or, in the Investigator's judgment, make the participant inappropriate for the study. Includes venous access that would be too difficult to facilitate repeated blood sampling.