Study of Glycerol Phenylbutyrate & Sodium Phenylbutyrate in Phenylbutyrate Naïve Patients With Urea Cycle Disorders (UCDs)

This is a randomized, controlled, open-label parallel arm study to assess the safety, tolerability, pharmacokinetics and ammonia control, of RAVICTI® as compared to Sodium phenylbutyrate (NaPBA) in urea cycle disorder subjects not currently or previously chronically treated with phenylacetic acid (phenylacetate; PAA) prodrugs. The study design will include: 1) Baseline Period; 2) Initial Treatment Period; 3) a RAVICTI only Transition Period 4) a RAVICTI only Maintenance Period; and 5) a RAVICTI only Safety Extension Period. The study will run for approximately 25 weeks.