The main purpose of this study is to determine if tadalafil can slow the decline in walking ability of boys who have Duchenne muscular dystrophy (DMD). The study will also assess the safety of tadalafil and any side effects that might be associated with it in boys who have DMD. Participants will receive study treatment (tadalafil or placebo) for the first 48 weeks of the study, and can then continue into an open label extension (OLE) that consists of two periods during which all participants will receive tadalafil. In OLE period 1, all participants will receive tadalafil for 48 weeks. Participants completing OLE period 1 will continue into OLE period 2 and will receive tadalafil for at least another 48 weeks.
Administered orally
Caba, Argentina