Randomized , double-blind , placebo-controlled study ; males 5 years with nm-dystrophinopathy received study drug orally 3 times daily , ataluren 10 , 10 , 20 mg/kg ( N = 57 ) ; ataluren 20 , 20 , 40 mg/kg ( N = 60 ) ; or placebo ( N = 57 ) for 48 weeks .