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

  • End date
    Mar 3, 2023
  • participants needed
  • sponsor
    Horizon Therapeutics, LLC
Updated on 3 May 2022
genetic testing
phenylacetic acid


This is a randomized, controlled, open-label parallel arm study to assess the safety, tolerability, pharmacokinetics and ammonia control, of RAVICTI® as compared to 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.

Condition Urea Cycle Disorder
Treatment RAVICTI, NaPBA
Clinical Study IdentifierNCT03335488
SponsorHorizon Therapeutics, LLC
Last Modified on3 May 2022


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Inclusion Criteria

Signed informed consent given by the subject or the subject's parent/legal guardian for those under 18 years of age or the age of consent by local regulation
Male and female subjects with a suspected or confirmed UCD diagnosis of any subtype, except NAGS deficiency
Suspected diagnosis is defined as having experienced a HAC or a documented high ammonia of >=100 µmol/L
Confirmed diagnosis is determined via enzymatic, biochemical, or genetic testing
Requires nitrogen-binding agents according to the judgment of the Investigator
Birth and older
All females of childbearing potential and all sexually active males must agree to use an acceptable method of contraception from signing the informed consent throughout the study and for 30 days after the last dose of study drug. Acceptable forms of contraception are (oral, injected, implanted or transdermal), tubal ligation, intrauterine device, hysterectomy, vasectomy, or double barrier methods. Abstinence is an acceptable form of birth control, though appropriate contraception must be used if the subject becomes sexually active

Exclusion Criteria

Subject has received chronic treatment with an oral phenylbutyrate (RAVICTI, NaPBA, Pheburane, or other) longer than 14 consecutive days within one year prior to enrollment
Temporary use of NaPBA for acute management of a hyperammonemic crisis in the past is acceptable
Any concomitant illness (e.g., malabsorption or clinically significant liver or bowel disease) which would preclude the subject's safe participation, as judged by the Investigator
Has undergone liver transplantation, including hepatocellular transplant
Subjects on NaBz at Baseline will be excluded if they are viewed by the Investigator as being unable to undergo NaBz transition to a PAA prodrug during the Initial Treatment Period
Known hypersensitivity to PBA or any excipients of the NaPBA/PBA formulations
Pregnant or breast-feeding patients. Women of childbearing potential must have a pregnancy test performed at the Baseline Visit prior to the start of study drug
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If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

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Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

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