A Study of the Safety, Efficacy and Pharmacokinetics of Glycerol Phenylbutyrate in Pediatric Subjects Under 2 Years of Age With Urea Cycle Disorders

An Open Label Study of the Safety, Efficacy and Pharmacokinetics of Glycerol Phenylbutyrate (GPB; RAVICTI®) in Pediatric Subjects Under Two Years of Age With Urea Cycle Disorders (UCDs)

This is an open-label study consisting of a transition period to RAVICTI, followed by a safety extension period for at least 6 months and up to 24 months of treatment with RAVICTI, depending on age at enrollment. It is designed to capture information important for evaluating safety, pharmacokinetics and efficacy in young children.

Subjects who are followed by or referred to the Investigator for management of their UCD. Subjects eligible for this study will include patients ranging from newborn to < 2 years of age with either a diagnosed or clinically suspected UCD.

Study acquired from Horizon in 2024.

Inclusion Criteria:

• Male and female subjects up to 2 years of age
• Signed informed consent by subject's parent/legal guardian
• UCD diagnosis or suspected diagnosis of any subtype, except N-acetyl glutamate synthetase deficiency. If UCD has not been previously confirmed by genetic testing, consent must be obtained from parent/legal guardian prior to perform genetic testing. If genetic testing is inconsistent with or excludes a UCD diagnosis, the subject will be withdrawn from the study.

Exclusion Criteria:

• Use of any investigational drug within 30 days of Day 1
• Uncontrolled infection (viral or bacterial) or any other condition known to precipitate hyperammonemic crises. Once these precipitating factors are medically controlled, patients presenting in crisis are eligible.
• Any clinical or laboratory abnormality of Grade 3 or greater severity according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.03, except Grade 3 elevations in ammonia and liver enzymes, defined as levels 5-20 times the upper limit of normal in alanine aminotransferase (ALT), aspartate aminotransferase (AST), or gamma glutamyl transpeptidase (GGT) in a clinically stable subject
• Any clinical or laboratory abnormality or medical condition that, at the discretion of the Investigator, may put the subject at increased risk by participating in this study
• Known hypersensitivity to phenylacetate (PAA) or phenylbutyrate (PBA)
• Liver transplantation, including hepatocellular transplant
• Subjects on hemodialysis at time of initiating RAVICTI
• Subjects on RAVICTI for UCD management
• Currently treated with Carbaglu® (carglumic acid)