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Citrulline Challenge Study for Healthy Subjects in the United Kingdom (CHS-UK)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02772861
Recruitment Status : Completed
First Posted : May 16, 2016
Last Update Posted : May 16, 2016
Information provided by (Responsible Party):
University College, London

Brief Summary:

There are many forms of small bowel disease but their direct consequences on small bowel function are often very hard, if not impossible, to establish. It would be helpful if there was a reliable blood test to find out how well cells in the intestine are working. The amino acid citrulline is produced mainly by these cells, and therefore holds promise as a biological marker. Some previous studies have shown that fasting citrulline gave a good indication as to how many intestinal cells were present. However, other authors have not been able to confirm this.

Most of the citrulline in the blood is derived from another amino acid, glutamine, in a metabolic process that occurs in the intestinal cells, and most of the remainder comes from another amino acid, arginine. A further potential marker of intestinal cell function is the amino acid 3-methylhistidine. It is possible that a dynamic test, which incorporates time for conversion from one amino acid to another in the intestinal cells, might perform better.

The investigators therefore propose a study of oral glutamine, arginine, and 3-methylhistidine compared with citrulline itself or placebo (glucose) as it is hypothesized that these might increase the amount of citrulline more reproducibly. An initial study in healthy subjects is required to establish whether this is true, and if so to provide a normal range prior to investigation of patients who have or who might have the short bowel syndrome, and in whom the test would be clinically useful.

In this study, the subjects will take each of the amino acids and placebo in random order. Between each 6 hour-long visit the subjects will have at least one week where they are independent of the research team and during which they can behave normally. During each visit subjects will have a sequence of blood samples from an in-dwelling venous cannula, taken before and over 6 hours after a single small oral dose of that day's amino acid given as a small volume drink. Urine will also be collected for amino acid assay.

Condition or disease Intervention/treatment Phase
Intestinal Diseases Dietary Supplement: Amino Acid Supplement - One dose Dietary Supplement: 3-Methylhistidine Not Applicable

Detailed Description:

Purpose and Design The purpose of the study is to determine the value of measuring citrulline after oral challenge, aiming to examine this as a function of enterocyte mass in patients with short bowel syndrome. The investigators hope to accumulate sufficient preliminary data in order to develop a new biochemical test for assessing absorption in future patient groups.

All subjects will provide written informed consent prior to their inclusion in the study. The study will be performed in accordance with International Conference on Harmonisation Guidelines for Good Clinical Practice (ICH GCP), the Helsinki Declaration and national regulations. Information about the study will be provided during one-on-one interviews with the help of a summary brochure which will be given to all potential subjects.

The study has been considered by the UK Medicines Agency, Medicines and Healthcare products Regulatory Agency (MHRA), and they agree that it is not a clinical trial of an investigational medicinal product.


  1. Potential participants will be identified by the investigator's team. The sources will include hospital and investigator databases.
  2. If permitted, advertisements will be posted for this study on University College London (UCL) electronic news sites, disseminated via UCL staff and student emails, with fliers to be posted on physical notice boards at UCL. Direct invitations from the researchers may also be attempted.
  3. Healthy volunteers will be offered £7.85/hour for their participation in this study.

Consent Written informed consent will be obtained before any study-specific procedures are carried out.

All participants will be free to withdraw from the study at any time.

Risk, burdens and benefits Apart from the small risks associated with venous access the study is expected to be without important hazard. The agents to be administered are essentially constituents of the normal diet.

There is no expectation that participants will benefit from being in this study.

Confidentiality All data provided to the sponsor or designee will be identified only by subject number or initials, thereby ensuring that the subject's identity remains unknown.

What will happen at the end of the study? Participants will be given a summary of the key results and the opportunity for further discussion on request.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Official Title: Randomised Cross-over Single-site Study on the Bioavailability of Citrulline After an Oral Bolus of Citrulline, Glutamine, Arginine, 3-Methylhistidine or Placebo in Healthy Subjects
Study Start Date : August 2011
Actual Primary Completion Date : May 2012
Actual Study Completion Date : May 2012

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Experimental: Citrulline
Citrulline is a non-protein amino acid that is present in substantial amounts in watermelon (Citrullus vulgaris), with a mean content of 2.1 mg/g fresh weight, ranging from 0.5 to 3.6 mg/g according to variety. The oral dose can reach 20 g, which was administered orally in the present study in one single dose, followed by a washout period of one week Amino Acid Supplement - One dose
Dietary Supplement: Amino Acid Supplement - One dose

Experimental: Glutamine

L-glutamine is a protein amino acid found in proteins of all life forms. It is classified as a semi-essential or conditionally essential amino acid. This means that under normal circumstances the body can synthesize sufficient l-glutamine to meet physiological demands. However, there are conditions where the body cannot do so. Recently, l-glutamine has come to be regarded as one of the most important of the amino acids when the body is subjected to such metabolic stress situations as trauma (including surgical trauma), cancer, sepsis and burns. In the present study, glutamine was administered orally in one single dose of 20 g, followed by a washout period of one week.

Amino Acid Supplement - One dose

Dietary Supplement: Amino Acid Supplement - One dose

Experimental: Arginine

Arginine was administered orally in 20 g for one single dose, followed by a washout period of 1 week.

Amino Acid Supplement - One dose

Dietary Supplement: Amino Acid Supplement - One dose

Experimental: 3-Methyl-Histidine

This amino acid is made by methylation of the actin and myosin peptide chains in the muscle. Metabolism after intravenous administration of L-3-methylhistidine involves excretion in the urine of 75% of the administered dose in 24 h and 95% in 48 h.

3-Methyl-Histidine was administered orally in 120 mg for one single dose, followed by a washout period of 1 week.

Dietary Supplement: 3-Methylhistidine

Placebo Comparator: Placebo
Dextrose (glucose) was used in a dose of 20 g in this study.
Dietary Supplement: Amino Acid Supplement - One dose

Primary Outcome Measures :
  1. Area Under the Curve (AUC) for citrulline [ Time Frame: predose, 15,30,45,60,90,120,180,360 minutes post-dose ]
    The primary end point for this study will be the Area Under the Curve (AUC) for citrulline after each oral load. This is the fraction of the administered dose that reaches the systemic circulation. Bioavailability is 100% for intravenous injection. It varies for other routes depending on incomplete absorption, first pass hepatic metabolism etc. Thus one plots plasma concentration against time, and the bioavailability is the AUC. The analysis of this continuous pharmacokinetic parameter will be performed on the plasma concentration-time data, using Statistical Package for the Social Sciences (SPSS) 17.0, Stata 10.0, Statistical Analysis System (SAS) and Sigma Plot.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  1. Healthy volunteers fasted for at least 12 hours
  2. Males and females aged at least 18

Exclusion Criteria:

  1. Consumption of coffee or alcohol within 12 hours
  2. Pregnancy
  3. Use of any regular medication
  4. Any significant past medical history

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02772861

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United Kingdom
University College, London
London, United Kingdom, NW1 2BU
Sponsors and Collaborators
University College, London
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Principal Investigator: Alastair Forbes, MD, FRCP University College London, Centre for Gastroenterology
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Responsible Party: University College, London Identifier: NCT02772861    
Other Study ID Numbers: 10/0458
First Posted: May 16, 2016    Key Record Dates
Last Update Posted: May 16, 2016
Last Verified: May 2016
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Additional relevant MeSH terms:
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Intestinal Diseases
Gastrointestinal Diseases
Digestive System Diseases