Citrulline (L-citrulline and citrulline malate) trials recruiting now
11 registrations that name citrulline as a study arm and are recruiting or about to, as ClinicalTrials.gov listed them on Oct 20, 2026. Read each listing for its full criteria and current status.
Kymata never assesses eligibility. Each listing names its own criteria; only its study team can say whether someone can join. Trial doses are given under the trial's monitoring and are not a schedule for anyone outside it.
Filter 11 registrations
Status
Phase
10US sites across 9 states
1
2 to 4
5 to 19
20 or more
All 11 registrations
RecruitingNCT06635902
Intravenous L-Citrulline for Vaso-occlusive Pain Episode in Sickle Cell Disease
Phase 2
Suvankar Majumdar
About 99 people
Started Dec 22, 2024
In plain words A Phase 2 study of citrulline in people 4 to 21, run by Suvankar Majumdar. It plans to enroll about 99 people at 1 US site.
Who it lists and where
Who the trial lists, as registered
Lists people 4 to 21. Conditions: Sickle Cell Disease; Vaso-occlusive Pain Episode.
Sickle cell disease (all genotypes)
Patients with sickle cell disease ages 4 to 21 years old
Presence of sickle cell vaso-occlusive pain episode requiring hospitalization and parenteral opioid therapy
Able to randomize to study drug/placebo within 12 hours of first dose of parenteral opioid in the Emergency Department
The exclusion criteria are on the listing.
What it tests, as registered
L-citrulline; Placebo; L-citrulline
Registered summary
The goal of this clinical trial is to learn if intravenous citrulline works to treat acute pain in hospitalized patients with sickle cell disease. It will also learn about the safety of intravenous citrulline. The main questions it aims to answer are: * Does intravenous citrulline decrease the duration of sickle cell pain during hospitalization * What medical problems do participants have when taking intravenous citrulline? Researchers will compare intravenous citrulline to a placebo (a look-alike substance that contains no drug) to see if intravenous citrulline works to treat acute pain. The full summary is on the listing.
Where, as registered
1 US site in 1 state.
RecruitingNCT06312748
Novel Approaches for Improving Vascular Function in Veterans With HFpEF
Phase 1
VA Office of Research and Development
About 90 people
Started May 19, 2021
In plain words A Phase 1 study of citrulline in people 18 and older, run by VA Office of Research and Development. It plans to enroll about 90 people at 1 US site.
Who it lists and where
Who the trial lists, as registered
Lists people 18 and older. Conditions: Heart Failure With Preserved Ejection Fraction; Inflammation.
Age 18 years or older and able to give written informed consent.
New York Heart Association (NYHA) functional class I, II, or III.
Left Ventricular Ejection Fraction (LVEF) > 50%.
Plasma Brain Natriuretic Peptide (BNP) equal to or greater than 150 pg/mL or NT-proBNP equal to or greater than 600 pg/mL at Visit 1, or a BNP equal to or great than 100 pg/mL (or NT-proBNP equal to or greater than 400 pg/mL) and a…
The exclusion criteria are on the listing.
What it tests, as registered
L-Citrulline; Placebo for L-Citrulline; BH4; Placebo for BH4; Atorvastatin; Placebo for Atorvastatin
Registered summary
This project will evaluate the impact of L-Citrulline, tetrahydrobiopterin (BH4), and atorvastatin administration on physical capacity and vascular function in Veterans with heart failure with preserved ejection fraction (HFpEF).
Where, as registered
1 US site in 1 state.
RecruitingNCT05259904
Study to Improve Deployment Related Asthma by Using L-Citrulline Supplementation
Phase 2
University of Colorado, Denver
About 75 people
Started Mar 8, 2023
In plain words A Phase 2 study of citrulline in people 18 to 70, run by University of Colorado, Denver. It plans to enroll about 75 people at 1 US site.
Who it lists and where
Who the trial lists, as registered
Lists people 18 to 70. Conditions: Post Deployment Related Asthma; Asthma.
Adequate completion of informed consent process with written documentation
Male and female patients, 18 - 70 years old, inclusive
Meets criteria for deployment related asthma or DRA (New onset of persistent respiratory symptoms of cough, dyspnea, wheezing and/or chest tightness during or after post-9/11/2001 military deployment to Southwest Asia, accompanied by a…
Able to perform reproducible spirometry according to ATS criteria
3 more inclusion criteria and the exclusion criteria are on the listing.
What it tests, as registered
L-citrulline; Placebo
Registered summary
Service men and women returning from deployment are significantly more likely to develop asthma and severe respiratory symptoms from airway obstruction. Why this happens is not well known, but exposure to diesel, burn pits, biomass smoke, and sandstorms are thought to play a role. Ultimately, patients with deployment related asthma develop a complex airway disease that does not respond well to standard asthma medications. Therefore, it is imperative that safe and affordable treatments that could improve quality of life and symptoms are studied. The full summary is on the listing.
Where, as registered
1 US site in 1 state.
RecruitingNCT07854223
Effects of Pre-Run Nutritional Supplements During a Fixed-Pace 5 km Treadmill Run
No phase
St. Louis University
About 20 people
Starts Oct 2026 (estimated)
In plain words A study of citrulline in people 18 to 35, run by St. Louis University. It plans to enroll about 20 people at 1 US site.
Who it lists and where
Who the trial lists, as registered
Lists people 18 to 35; healthy volunteers accepted. Conditions: Exercise Physiology; Nutritional Supplementation.
Age 18-35 years
Healthy adult
Able to provide written informed consent
Regularly engaged in running-based aerobic training at least 3 times per week for at least 30 minutes per session during the past 3 months
3 more inclusion criteria and the exclusion criteria are on the listing.
This study will examine how three commonly used pre-run nutritional supplements-caffeine, L-citrulline, and an exogenous ketone supplement-affect physiological and perceptual responses during a fixed-pace 5 km treadmill run in healthy, physically active runners. Participants will complete one screening and baseline visit followed by four experimental visits in a randomized order. At each experimental visit, participants will receive caffeine, L-citrulline, an exogenous ketone supplement, or placebo before completing a fixed-pace 5 km treadmill run. The full summary is on the listing.
Where, as registered
1 US site in 1 state.
RecruitingNCT05934318
L-ArGinine to pRevent advErse prEgnancy Outcomes (AGREE)
No phase
Liverpool School of Tropical Medicine
About 2,960 people
Started Dec 29, 2023
In plain words A study of citrulline in female participants 16 to 40, run by Liverpool School of Tropical Medicine. It plans to enroll about 2,960 people at 1 site, none in the US.
inclusive to 24 weeks gestational age as confirmed by ultrasound,
who have a viable singleton pregnancy,
are residents of the study area,
2 more inclusion criteria and the exclusion criteria are on the listing.
What it tests, as registered
L-citrulline
Registered summary
There are few safe, effective, and affordable interventions to improve pregnancy outcomes in low resource settings where the highest rates of poor birth outcomes occur. L-citrulline is naturally found in many foods and is changed into another important amino acid, L-arginine, in the body. L-arginine is important for the growth of a healthy placenta and healthy baby. The full summary is on the listing.
Where, as registered
No US site; Kenya (1).
RecruitingNCT06426147
L-citrulline to Improve Adverse Outcomes in Admitted Children (EChiLiBRiST, Clinical Trial 2, Inpatients)
No phase
Barcelona Institute for Global Health
About 2,200 people
Started Dec 8, 2025
In plain words A study of citrulline in people 0 months to 60 months, run by Barcelona Institute for Global Health. It plans to enroll about 2,200 people at 2 sites, none in the US.
Who it lists and where
Who the trial lists, as registered
Lists people 0 months to 60 months. Conditions: Infectious Disease; Infections; Child, Only.
Enrolled in the initial prognostic screening component.
Sick children with fever (axillary temperature>37.5ºC) or a history of fever (within the preceding 72h) or with suspected severe disease.
1m-<60 months of age.
With an indication for admission, or having already been admitted to hospital due to their illness.
4 more inclusion criteria and the exclusion criteria are on the listing.
What it tests, as registered
L-citrulline; Placebo
Registered summary
In low and middle-income countries, children admitted to hospital are not similarly ill, and do not all have a comparable prognosis. In fact, understanding at first encounter their risk of developing adverse outcomes (including mortality) could allow a more focused management and the tailoring of specific interventions to decrease in hospital mortality, and post discharge adverse longer-term outcomes. The full summary is on the listing.
Where, as registered
No US site; Ethiopia (1), Mozambique (1).
RecruitingNCT07642505
L-Citrulline and Tadalafil for Mild to Moderate Erectile Dysfunction
Phase 4
Beni-Suef University
About 133 people
Started Jun 8, 2026
In plain words A Phase 4 study of citrulline in male participants 30 to 70, run by Beni-Suef University. It plans to enroll about 133 people at 1 site, none in the US.
Who it lists and where
Who the trial lists, as registered
Lists male participants 30 to 70. Conditions: Erectile Dysfunction.
Male patients aged 30 to 70 years.
Erectile dysfunction for at least 3 months.
Mild to moderate erectile dysfunction, defined by International Index of Erectile Function-Erectile Function domain score from 11 to 25.
Stable sexual relationship during the study period.
3 more inclusion criteria and the exclusion criteria are on the listing.
Erectile dysfunction is a common male sexual health problem that may affect quality of life and sexual relationships. Tadalafil 5 mg once daily is an established oral treatment for erectile dysfunction. L-citrulline is an oral nitric oxide pathway supplement that may improve erectile function by increasing L-arginine availability. This randomized trial will compare three oral treatment regimens in men with mild to moderate erectile dysfunction: L-citrulline 1500 mg/day, tadalafil 5 mg/day, and the combination of L-citrulline 1500 mg/day plus tadalafil 5 mg/day. The full summary is on the listing.
Where, as registered
No US site; Egypt (1).
RecruitingNCT04513288
ICITRU : Randomized Trial of Immunonutrition With L-citrulline in Patients Hospitalized in Intensive Care for Sepsis or Septic Shock
No phase
Rennes University Hospital
About 130 people
Started May 20, 2022
In plain words A study of citrulline in people 18 and older, run by Rennes University Hospital. It plans to enroll about 130 people at 5 sites, none in the US.
Who it lists and where
Who the trial lists, as registered
Lists people 18 and older. Conditions: Sepsis; Septic Shock.
Septic patients in accordance with the definition of sepsis and septic shock published in 2016 (JAMA) and whose use is recommended by the European Society of Intensive Care Medicine;
Initial aggression dated less than 4 days before admission to intensive care (selection of "community" patients). The onset of aggression will be defined by the onset of clinical signs of infection;
Patients hospitalized for less than 48 hours before admission to intensive care (selection of patients without malnutrition and immunosuppression acquired in hospital) *;
Patients under invasive mechanical ventilation with a foreseeable ventilation duration> 2 days **;
9 more inclusion criteria and the exclusion criteria are on the listing.
Immunonutrition in intensive care has not yet demonstrated a beneficial effect on organ failure, the acquisition of nosocomial infections, or mortality. It did not correct for acquired immunosuppression in intensive care patients. Despite numerous methodological problems (use of several pharmaconutrients, very heterogeneous set of patients) and the absence of clinical data, deleterious effects have been attributed to immunonutrition in intensive care, in particular in septic patients and patients in intensive care . The full summary is on the listing.
Where, as registered
No US site; France (5).
RecruitingNCT07617909
L-Citrulline Versus Tamsulosin for Medical Expulsive Therapy of Distal Ureteral Stones
Phase 2
Beni-Suef University
About 120 people
Started May 6, 2026
In plain words A Phase 2 study of citrulline in people 18 to 60, run by Beni-Suef University. It plans to enroll about 120 people at 1 site, none in the US.
Who it lists and where
Who the trial lists, as registered
Lists people 18 to 60. Conditions: Distal Ureteral Stone; Urolithiasis; Ureteral Calculi.
Adults aged 18 to 60 years.
Single distal ureteral stone.
Stone size 5 to 10 mm.
Normal renal function.
3 more inclusion criteria and the exclusion criteria are on the listing.
What it tests, as registered
L-Citrulline; Tamsulosin
Registered summary
This study will compare L-citrulline and tamsulosin as medical expulsive therapy for adults with single distal ureteral stones. Eligible participants with a single distal ureteral stone measuring 5 to 10 mm will be randomly assigned to receive either oral L-citrulline 750 mg twice daily or oral tamsulosin 0.4 mg once daily. Treatment will continue until documented stone passage or completion of 4 weeks of therapy, whichever occurs first. Participants will be followed weekly for up to 4 weeks. The main outcome is stone expulsion within 4 weeks. The full summary is on the listing.
Where, as registered
No US site; Egypt (1).
RecruitingNCT05636397
Safety and PK-PD Study of Oral L-CIT in Preterm Infants With BPD±PH and NEC
No phase
The Hospital for Sick Children
About 36 people
Started Nov 1, 2023
In plain words A study of citrulline in people 1 month to 6 months, run by The Hospital for Sick Children. It plans to enroll about 36 people at 1 site, none in the US.
Who it lists and where
Who the trial lists, as registered
Lists people 1 month to 6 months. Conditions: BPD - Bronchopulmonary Dysplasia; Pulmonary Hypertension; NEC.
Born ≤ 30 weeks at birth
Post-menstrual age (PMA) ≥ 32 weeks
Echocardiographic evidence of PH for infants with BPD+PH.
On invasive or non-invasive ventilation with RSS >2.0 for >12hours/day for at least 48 hours as an early predictor of evolving BPD
1 more inclusion criterion and the exclusion criteria are on the listing.
What it tests, as registered
L-Citrulline
Registered summary
The purpose of this study is to evaluate the safety and explore the PK/PD of L-CIT supplementation in preterm infants to prevent the development of inflammatory pathways initiated by low levels of plasma CIT, specifically in preterm infants with post-surgical NEC and BPD±PH.
Where, as registered
No US site; Canada (1).
Not yet recruitingNCT06989567
A Study of Intravenous L-Citrulline in Patients Aged 6-21 Years Old With Sickle Cell Disease Presenting to Emergency Departments in Acute Vaso-Occlusive Crisis
Phase 3
Asklepion Pharmaceuticals, LLC
About 120 people
Starts Jul 25, 2025 (estimated)
In plain words A Phase 3 study of citrulline in people 6 to 21, run by Asklepion Pharmaceuticals, LLC. It plans to enroll about 120 people at 6 US sites.
Who it lists and where
Who the trial lists, as registered
Lists people 6 to 21. Conditions: Sickle Cell Disease.
SCD (all genotypes)
Children, adolescents and young adults between ages 6 to 21 years
In a steady disease state and not in the midst of any acute complication other than VOC due to SCD at study entry
Baseline NRS score >5 or Faces Pain Scale score ≥6
3 more inclusion criteria and the exclusion criteria are on the listing.
What it tests, as registered
L-citrulline; Placebo
Registered summary
This study is being done to learn more about a possible new treatment for pain episodes (called vaso-occlusive crises or VOCs) in children, teens, and young adults with sickle cell disease (SCD). The study will include about 120 participants between the ages of 6 and 21 who come to the emergency department (ED) with a VOC. A VOC is a painful episode that happens with no clear cause and no signs of infection or major problems with organs like the liver or kidneys. The full summary is on the listing.