The Objective of This Study Was to Compare and Quantify the Bioavailability of Citrulline Byproducts in Blood Samples and in Urine Samples After a Single Dose of the Assigned Dietary Supplement. The Treatment Arms Containing the Following Molecules: Citrulline HCL and L-Citrulline,

A SINGLE CENTER, SINGLE-BLIND STUDY DESIGN IN HEALTHY SUBJECTS TO EVALUATE SEVERAL EFFECTS OF CITRULLINE SUPPLEMENTS

Citrulline dietary supplements are of interest for improving cardiovascular and exercise performance. The health benefits of citrulline are attributable to its ability to increase arginine levels in the body through the intestinal-renal arginine conversion pathway. From a dietary supplementation standpoint, citrulline offers advantages over arginine due to its reduced first-pass metabolism and ready conversion to arginine within the body. While L-citrulline is the most widely used citrulline dietary supplement, additional salt forms such as citrulline maleate and citrulline HCl may provide improvements in the delivery of arginine to the body. The present study compared the single-dose pharmacokinetics of L-citrulline and citrulline HCl formulations in healthy human subjects. A total of 17 subjects were randomly assigned to groups receiving either 6 g of L-citrulline, 6 g of citrulline HCl or 2 g of citrulline HCl. The resulting increases in citrulline and arginine in plasma and urine samples were determined using liquid chromatography-multiple reaction monitoring mass spectrometry (LC-MRM/MS). All citrulline dietary supplements examined produced time-dependent increases in plasma citrulline and arginine. Both maximal plasma concentration (Cmax) and area under the plasma vs time curve (AUC) for citrulline were modestly reduced in the 6 g citrulline HCl treatment group, the resulting arginine Cmax and AUCs were similar for both L-citrulline and citrulline HCl at the 6 g dose. While the 2 g dose of citrulline HCl had reduced Cmax and AUC values compared to 6 g doses, the time to reach peak levels of arginine were significantly shorter. Furthermore, examination of the relative arginine bioavailability achieved with the 6 g and 2 g citrulline HCl compared to the 6 g L-citrulline was approximately 120% and 215%, respectively, consistent with an improved citrulline to arginine conversion efficiency with the citrulline HCl formulations.

Study Overview

• Status: Completed
• Conditions: Bioavailability and AUC
• Intervention / Treatment: Other: Removal from study. In case of adverse event, subject treated for the AE.; Other: removal from study

• Study Type: Observational
• Enrollment (Actual): 32

Contacts and Locations

Study Locations

• United States
  • New Jersey
    • Raritan, New Jersey, United States, 08869
      • Princeton Consumer Research

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

healthy males and females ages 18-64

Description

Inclusion Criteria:

• healthy and hydrated male or female ages 18-64; agrees to refrain from citrulline-rich foods; able and willing to fast 12 hours prior to baseline visit; willing to have blood and urine collections as dictated in the protocol; females of child bearing age have some type of birth control.

Exclusion Criteria:

• female subject is pregnant; allergies or sensitivities to citrulline products; history of losing consciousness during blood collection;past medical history of iron deficiency; history of or current treatment for hypertension, coronary heart disease; or angina pectoris; known kidney function issues or disorders; being treated with ACE inhibitors; cancer diagnosis within 5 years of visit; history of chronic disease.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Generally healthy male and female subjects aged 18-64

Other: Removal from study. In case of adverse event, subject treated for the AE.; The participation of a subject in this study may have been discontinued for any of the following reasons: the subject wished to withdraw from study participation;; if, in the opinion of the Investigator, it was in the best interest of the subject;; suspected adverse effects from the test article;; inter-current illness;; violation of the prohibitions and restrictions;; development of an exclusion criteria. Subjects were free to withdraw at any time and need not give a reason, however, every reasonable attempt was made to ascertain such reasons. The data for those subjects who were withdrawn was included in the final clinical report but may be excluded from final data analysis.; Other: removal from study; The participation of a subject in this study may have been discontinued for any of the following reasons: the subject wished to withdraw from study participation;; if, in the opinion of the Investigator, it was in the best interest of the subject;; suspected adverse effects from the test article;; inter-current illness;; violation of the prohibitions and restrictions;; development of an exclusion criteria. Subjects were free to withdraw at any time and need not give a reason, however, every reasonable attempt was made to ascertain such reasons. The data for those subjects who were withdrawn was included in the final clinical report but may be excluded from final data analysis.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Arginine levels in plasma	Measured blood plasma arginine levels at various time points.	0-180 minutes

Collaborators and Investigators

• Sponsor: Vireo Systems, Inc.
• Collaborators: Princeton Consumer Research

Study record dates

Study Major Dates

• Study Start (Actual): July 13, 2024
• Primary Completion (Actual): July 27, 2024
• Study Completion (Actual): July 27, 2024

Study Registration Dates

• First Submitted: May 9, 2025
• First Submitted That Met QC Criteria: May 9, 2025
• First Posted (Actual): May 18, 2025

Study Record Updates

• Last Update Posted (Actual): May 18, 2025
• Last Update Submitted That Met QC Criteria: May 9, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Keywords: Citrulline,Arginine
• Other Study ID Numbers: VIRUSE2R

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No