RecruitingNCT05299710
Metabolic
Urea Cycle Disorders
Also known as UCD, OTC deficiency, ornithine transcarbamylase deficiency, citrullinemia
Urea cycle disorders (UCDs) are a group of inherited metabolic diseases in which the liver cannot convert ammonia to urea for excretion. The most common form is OTC (ornithine transcarbamylase) deficiency, which is X-linked.
17
studies recruiting now
as of 7 Sept 2026
116
studies registered in total
as of 7 Sept 2026
4
countries with a recruiting site
as of 7 Sept 2026
14 Jul 2026
most recent study posted
among recruiting studies
Recruiting trials
RecruitingNCT06805695
Long-term Follow-up (LTFU) Study of Participants in Any iECURE Protocol Using an Investigational Product (IP)
RecruitingPhase 1 / Phase 2NCT07667387
Study of LNP.UCD.ABE in Patients With Urea Cycle Disorders
RecruitingPhase 3NCT06255782
An Open-label Study to Investigate ECUR-506 in Male Babies Less Than 9 Months of Age With Neonatal Onset OTC Deficiency
RecruitingNCT07701694
Functional Evaluation in Patients With Urea Cycle Disorders (UCD) During a Driving Task
Showing the 5 most recently updated recruiting studies, as recorded 7 Sept 2026. Live status on each study page.
See all 17 recruiting studiesWhere recruiting studies are running
Countries with at least one recruiting site among the studies above, 7 Sept 2026. Tap a country to search trials there.
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About Urea Cycle Disorders
Urea cycle disorders (UCDs) are a group of inherited metabolic diseases in which the liver cannot convert ammonia to urea for excretion. The most common form is OTC (ornithine transcarbamylase) deficiency, which is X-linked. Accumulation of ammonia (hyperammonemia) is the central toxic event, causing encephalopathy that can be life-threatening, particularly in neonates. Long-term management includes protein-restricted diet, nitrogen scavenger drugs, and in severe cases liver transplantation.
Common clinical features
HyperammonemiaEncephalopathyLethargy and vomitingProtein aversionLiver dysfunctionIntellectual disabilityCoagulopathy
From Orphanet’s phenotype annotations (CC BY 4.0). Not a complete list.
Treatments being studied
3 approved treatments and 2 in clinical development, from Open Targets (CC BY 4.0). Not medical advice.
Approved: Glycerol Phenylbutyrate (Ravicti)Approved: Sodium Phenylbutyrate (Ambutyrate)Approved: Phenylbutyrate Sodium
Phase 2Onterodrimer
Phase 1/2Acetohydroxamic Acid (Lithostat)
Before you apply
Things trial teams commonly ask about for Urea Cycle Disorders. Not eligibility rules; those are set by each study.
- Specify the exact UCD subtype — OTC deficiency trials are separate from citrullinemia or argininosuccinic aciduria trials
- Plasma ammonia level and amino acid profile are required baseline biomarkers for most trials
- Nitrogen scavenger therapy (sodium benzoate, sodium phenylbutyrate, glycerol phenylbutyrate) use must be documented — some trials require stable dosing
- Liver transplantation corrects the metabolic defect — transplanted patients may be ineligible for gene therapy trials
Related conditions
Information, not medical advice. Trial listings are shown as recorded on ClinicalTrials.gov; whether any study is right for you is a decision for you and your clinicians, and eligibility is decided by each research team. Disease information from Orphanet (CC BY 4.0).