HealthyOCERA OPNCT03159390
Metabolism of Ornithine Phenylacetate
A study testing phenylacetate salt of ornithine in people with Healthy, run by Texas A&M University at 1 site in United States.
Trial summary
Intravenous infusion of stable tracers of ornithine, glutamine, glutamate, and glycine will be performed, and collect blood samples, urine samples, and muscle biopsies to evaluate the effect of a continuous oral intake of phenylacetate salt of ornithine (OP) on its metabolic fate. Read more about this study
- Who is it for?
- Ages 40 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy
- What is being tested?
- phenylacetate salt of ornithine
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteUnited States
- Study dates
- 3 Feb 2015to 30 Apr 2015
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 40 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Healthy male \& female according to the investigator's or appointed staff's judgment
- Age 40-70 years (to be comparable with patients with liver cirrhosis: average 54.1 +/- 9.4 years)
Who cannot join
- Metabolic diseases including diabetes and hepatic or renal disorders
- Presence of acute illness or metabolically unstable chronic illness
- Failure to give informed consent
- (Possible) pregnancy
- Any other condition according to the PI or nurse that would interfere with the study or safety of the patient or influence the results
- Unwilling to stop taking nutritional protein supplements within 5 days before test day
Show all 9Show fewer
- History of hypo- or hyper-coagulation disorders, including use of a Coumadin derivative, history of deep venous thrombosis (DVT), or pulmonary embolism (PE) at any point in lifetime
- Currently taking anti-thrombotics (i.e. medical indication) and cannot stop for 3-7 days prior to test days
- Allergy to local anesthetic
Trial locations and contacts
1 site in 1 country.
United States1 site
Texas A&M University-CTRAL
College Station, Texas, 77843-4253
About this study
Official title: Human Metabolism of Ornithine Phenylacetate: A Study in Healthy Volunteers
Intravenous infusion of stable tracers of ornithine, glutamine, glutamate, and glycine will be performed, and collect blood samples, urine samples, and muscle biopsies to evaluate the effect of a continuous oral intake of phenylacetate salt of ornithine (OP) on its metabolic fate.
Read the detailed description
The study involves 1 screening visit of approximately 1 hour and 4 study days of approximately 10 hours. The subject will be asked to arrive in the fasted state on all study days. Fasting prior to screening is not required. On the screening day, body weight and height will be measured and Dual-energy X-ray absorptiometry (DXA) will be performed to measure body composition. After 4 hours subjects received a continuous intravenous infusion with OP in a dosage of 1 g /h. Next to the stable tracers provided to determine OP metabolism, stable tracers of phenylalanine (PHE) and tyrosine (TYR) may be provided to determine the effect of OP on protein metabolism at plasma and muscle tissue level. This required 2 muscle biopsies and on 2 study days 1 set of stable tracer pulses.
- Conditions
- Healthy
- Being tested
- phenylacetate salt of ornithine
- Keywords
- dietary supplements
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
phenylacetate salt of ornithineOther
| Study group | Role | What they receive |
|---|---|---|
| phenylacetate salt of ornithine | Experimental | There are 4 study days of approximately 10 hours. Amino acid tracers (e.g., OP, PHE, TYR) will be provided via IV. The dosage of OP provided in this study 6 g in a period of 6 hours. 2 muscle biopsies will be completed on 2 of the study days. Receives: Other: phenylacetate salt of ornithine |
What is being measured
The primary outcome is the main question the study is designed to answer.
metabolism of ornithine phenylacetate to glutamate and glutamine
The incorporation of the N atoms of ORN into glutamate, and the quantitative contribution of both pathways will be traced, and when the enrichment of ORN and GLU is measured in muscle tissue, give an estimation of the importance of muscle OAT for this incorporation.
Measured: 4 study days that are 8 hours each
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 May 2017
- Study start3 Feb 2015
- Primary completion30 Apr 2015
- Study completion30 Apr 2015
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for HealthyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- Texas A&M University
- Sponsor type
- University, hospital or other
- Collaborators
- Ocera Therapeutics
- Responsible party
- Principal investigator, Marielle PKJ Engelen, PhD, Texas A&M University
- Investigators
- Marielle Engelen, PhD, Principal investigator, Texas A&M University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03159390
- Sponsor's protocol ID
- 2014-0801
- Acronym
- OCERA OP
- Status last verified
- Sep 2025
- First submitted
- 16 May 2017
- Last updated
- 30 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Huttl VN, Deutz N, Wierzchowska-McNew RA, Ruebush LE, Engelen M. Whole-body and intracellular arginine metabolism in hypertension: role of disease severity and sex. Am J Hypertens. 2026 May 18:hpag047. doi: 10.1093/ajh/hpag047. Online ahead of print.
PubMed 42149813Kang MC, Deutz NEP, Kirschner SK, Engelen MPKJ. Metabolic kinetics and muscle and brain health markers in older adults, and the role of age and presence of chronic morbidities: A large cross-sectional cohort study. Clin Nutr. 2024 Dec;43(12):36-47. doi: 10.1016/j.clnu.2024.10.015. Epub 2024 Oct 11.
PubMed 39423760
Study at a glance
From the registry record, last updated by the sponsor on 30 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Human Metabolism of Ornithine Phenylacetate: A Study in Healthy Volunteers
- ClinicalTrials.gov ID
- NCT03159390
- Acronym / sponsor ID
- OCERA OP / 2014-0801
- Conditions
- Healthy
- Keywords
- dietary supplements
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 20 participants (actual)
- Lead sponsor
- Texas A&M UniversityUniversity, hospital or other
- Collaborators
- Ocera Therapeutics
- Study start
- 3 Feb 2015 (actual)
- Primary completion
- 30 Apr 2015 (actual)
- Study completion
- 30 Apr 2015 (actual)
- First posted
- 18 May 2017 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Intravenous infusion of stable tracers of ornithine, glutamine, glutamate, and glycine will be performed, and collect blood samples, urine samples, and muscle biopsies to evaluate the effect of a continuous oral intake of phenylacetate salt of ornithine (OP) on its metabolic fate.
Detailed description
The study involves 1 screening visit of approximately 1 hour and 4 study days of approximately 10 hours. The subject will be asked to arrive in the fasted state on all study days. Fasting prior to screening is not required. On the screening day, body weight and height will be measured and Dual-energy X-ray absorptiometry (DXA) will be performed to measure body composition. After 4 hours subjects received a continuous intravenous infusion with OP in a dosage of 1 g /h. Next to the stable tracers provided to determine OP metabolism, stable tracers of phenylalanine (PHE) and tyrosine (TYR) may be provided to determine the effect of OP on protein metabolism at plasma and muscle tissue level. This required 2 muscle biopsies and on 2 study days 1 set of stable tracer pulses.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| phenylacetate salt of ornithine | Experimental | Other: phenylacetate salt of ornithineThere are 4 study days of approximately 10 hours. Amino acid tracers (e.g., OP, PHE, TYR) will be provided via IV. The dosage of OP provided in this study 6 g in a period of 6 hours. 2 muscle biopsies will be completed on 2 of the study days. |
Who may qualify
- Ages
- 40 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Healthy male \& female according to the investigator's or appointed staff's judgment
- Age 40-70 years (to be comparable with patients with liver cirrhosis: average 54.1 +/- 9.4 years)
Key exclusion criteria (9 listed)
- Metabolic diseases including diabetes and hepatic or renal disorders
- Presence of acute illness or metabolically unstable chronic illness
- Failure to give informed consent
- (Possible) pregnancy
- Any other condition according to the PI or nurse that would interfere with the study or safety of the patient or influence the results
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| phenylacetate salt of ornithine | Other | phenylacetate salt of ornithine |
Primary outcome
metabolism of ornithine phenylacetate to glutamate and glutamine
Time frame: 4 study days that are 8 hours each
The incorporation of the N atoms of ORN into glutamate, and the quantitative contribution of both pathways will be traced, and when the enrichment of ORN and GLU is measured in muscle tissue, give an estimation of the importance of muscle OAT for this incorporation.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Sep 2025.
- Derived from this study: PubMed 42149813Huttl VN, Deutz N, Wierzchowska-McNew RA, Ruebush LE, Engelen M. Whole-body and intracellular arginine metabolism in hypertension: role of disease severity and sex. Am J Hypertens. 2026 May 18:hpag047. doi: 10.1093/ajh/hpag047. Online ahead of print.
- Derived from this study: PubMed 39423760Kang MC, Deutz NEP, Kirschner SK, Engelen MPKJ. Metabolic kinetics and muscle and brain health markers in older adults, and the role of age and presence of chronic morbidities: A large cross-sectional cohort study. Clin Nutr. 2024 Dec;43(12):36-47. doi: 10.1016/j.clnu.2024.10.015. Epub 2024 Oct 11.
- Individual participant dataSharing planned: No
Related trials for Healthy
Recruiting
THE EFFECTS OF GAME-BASED EXERCISE PROGRAMS
Physical Activity, Body Image
Not yet recruitingPhase 1
A Phase I Study of GLR2053 Tablets in Chinese Healthy Adult Participants
Atopic Dermatitis
Recruiting
Colon-delivered Riboflavin and Gut Microbiota Composition
Microbiome Dysbiosis, Gut Health
Not yet recruiting
Neuroergonomic Analysis of a Brain-Computer Interface Device (BCI)
Healthy Volunteers - Male and Female
RecruitingPhase 1
First-in-Human Trial to Assess REGN20423 in Healthy Adult Participants and Adult Participants With Atopic Dermatitis
Healthy Volunteer, Atopic Dermatitis
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Marielle Engelen, PhD principal investigator
Texas A&M University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing phenylacetate salt of ornithine in people with Healthy, run by Texas A&M University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 30 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
metabolism of ornithine phenylacetate to glutamate and glutamine (time frame: 4 study days that are 8 hours each). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03159390, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Sep 2025.