This study is designed to evaluate safety, tolerability, and pharmacokinetics (PK) in male children with nmDMD aged ≥6 months to <2 years treated daily for 24 weeks with orally administered ataluren 10, 10, and 20 milligrams/kilogram (mg/kg) (morning, mid-day, and evening dose, respectively).

Participants who complete the 24-week treatment period in this study will be offered participation to a follow-up extension period for at least 52 weeks from the date of first administration of ataluren in this parent study.

Inclusion Criteria:

• Body weight ≥7.5 kilograms (kg)
• Diagnosis of duchenne muscular dystrophy (DMD) based on an elevated serum creatine kinase and genotypic evidence of dystrophinopathy.
• Documentation of the presence of a nonsense mutation of the dystrophin gene as determined by gene sequencing prior to enrollment.

Exclusion Criteria:

• Participation in any drug or device investigation or whose sibling is currently participating in a blinded portion of another ataluren study or received an investigational drug within three months prior to the Screening Visit or who anticipate participating in any other drug or device clinical investigation or receiving any other investigational drug within the duration of this study.

• Expectation of a major surgical procedure during the study period.

• Known hypersensitivity to any of the ingredients or excipients of the study drug (polydextrose, polyethylene glycol 3350, poloxamer 407, mannitol 25C, crospovidone XL10, hydroxyethyl cellulose, vanilla, colloidal silica, or magnesium stearate).

• Ongoing use of the following drugs:

  1. Systemic aminoglycoside therapy and/or intravenous (IV) vancomycin.
  2. Coumarin-based anticoagulants (for example, warfarin), phenytoin, tolbutamide, or paclitaxel.
  3. Inducers of UGT1A9 (for example, rifampicin), or substrates of OAT1 or OAT3 (for example, ciprofloxacin, adefovir, oseltamivir, aciclovir, captopril, furosemide, bumetanide, valsartan, pravastatin, rosuvastatin, atorvastatin, pitavastatin).