Glycerol phenylbutyrate for Chinese children and teens with urea cycle disorders

A Single-arm, Prospective, Multi-center Post-market Clinical Study of Glycerol Phenylbutyrate in Chinese Patients With Urea Cycle Disorders

This project will try glycerol phenylbutyrate in children and teens in China who have urea cycle disorders to see if it lowers ammonia and reduces hyperammonemic crises over five years.

Quick facts

• Study type: Observational
• Enrollment: 40 (estimated)
• Ages: 0 Years to 18 Years
• Sex: All
• Sponsor: Tongji Hospital (Academic / other)
• Locations: 5 sites (Beijing, Beijing Municipality and 4 other locations)
• Trial ID: NCT06904027 on ClinicalTrials.gov

What this trial studies

This is a multicenter, prospective, single-arm observational study enrolling up to 40 Chinese participants aged 0–18 with diagnosed urea cycle disorder subtypes who plan to start glycerol phenylbutyrate and have not used it in the prior three months. Patients are followed for a total of five years with visits at 1 and 3 months, then every six months, collecting ammonia levels, clinical labs, adverse events, hyperammonemic crises, medication dosing, growth measures, and neurocognitive outcomes. The study documents real-world safety, dosing, biochemical control, and clinical events while participants receive glycerol phenylbutyrate during routine care. Data will provide longitudinal descriptive outcomes to inform clinical management in Chinese pediatric UCD patients.

Who should consider this trial

Good fit: Children and adolescents (0–18 years) in China with a diagnosed UCD subtype (e.g., CPS1, OTC, citrullinemia type I, ASL deficiency, argininemia, HHH) who plan to start glycerol phenylbutyrate and have not used it in the past three months.

Not a fit: Adults over 18, patients with UCD subtypes not listed, or those already well controlled on alternative long-term regimens may not gain additional benefit from joining this observational program.

Why it matters

Potential benefit: If successful, the results could support glycerol phenylbutyrate as a long-term option to reduce ammonia levels and hyperammonemic crises and improve growth and neurocognitive outcomes in Chinese children with UCD.

How similar studies have performed: Previous international studies and clinical experience with glycerol phenylbutyrate (Ravicti) have shown reductions in ammonia levels and hyperammonemic events, and this study aims to document similar outcomes in Chinese pediatric patients.

Eligibility criteria

Inclusion Criteria:

1. Male or female aged 0-18 years;
2. Subject and/or subject's legally authorized representative willing to follow the therapeutic regimen, dietary management and visit plan of the study, and voluntarily signing informed consent form;
3. Patients with the following subtypes of UCD: Carbamoyl phosphate synthetase I deficiency, Ornithine translocase deficiency, citrullinemia type I, argininosuccinic aciduria, argininemia, and hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome;
4. Patients planned to use glycerol phenylbutyrate who have not used it in past 3 months (including at the time of 3 months);
5. Men with fertility and women of childbearing potential (with menstruation) who are willing to take effective contraceptive measures during the period from the date of signing the informed consent to 1 months after the last dose of the study drug, such as abstinence, condoms, intra-uterine contraceptive devices, and double barrier methods (such as condoms + contraceptive diaphragms). Pregnancy test results must be negative for women of childbearing age within ≤ 7 days before the initial administration of study drug.

Exclusion Criteria:

1. Hypersensitivity to any of the active ingredient, including phenylbutyrate (PBA), phenylacetate acid (PAA) and phenylacetyl glutamine (PAGN), or excipients;
2. Use of any drug known to significantly affect renal clearance (such as probenecid) or increase protein catabolism (such as corticosteroids) or other drugs known to increase blood ammonia levels (such as valproate) within 24 h before the first administration;
3. Use of other nitrogen-scavenging agent at the same time after enrollment, such as sodium phenylbutyrate and sodium benzoate;
4. Pregnant or breastfeeding females.
5. Other reasons, in the opinion of the investigator, that may affect the patient's compliance and safety in participating in the study.

Where this trial is running

Beijing, Beijing Municipality and 4 other locations

• Peking University First Hospital — Beijing, Beijing Municipality, China (Recruiting)
• Guangzhou Women and Children's Medical Center — Guangzhou, Guangdong, China (Recruiting)
• Tongji Hosipital — Wuhan, Hubei, China (Recruiting)
• Xinhua Hospital, Shanghai Jiao Tong University School of Medicine — Shanghai, Shanghai Municipality, China (Recruiting)
• Children's Hospital of Zhejiang University School of Medicine — Hangzhou, Zhejiang, China (Recruiting)

Study contacts

• Principal investigator: Xiaoping Luo, M.D. — Tongji Hospital
• Study coordinator: Xiaoping Luo, M.D.

Conditions Urea Cycle Disorders; Chinese; Pediatric patients; Urea cycle disorders; Glycerol phenylbutyrate