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L-Citrulline

Phase 3

Sickle Cell Disease | Small molecule | Hematology |Travere Therapeutics, Inc.|Trials Updated: May 29, 2025

L-Citrulline development status

Highest phase Phase 3
Registered trials 6 across 1 sponsor since Jun 2006

L-Citrulline target and mechanism

ModalitySmall molecule

Also known as Intravenous L-Citrulline

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials5
Total Enrollment473

FDA Designations

No designations recorded

L-Citrulline clinical trials

L-Citrulline · 5 trials · 8 indications

Phase 3 3Phase 2 1Phase 1 1
NCT06989567A Study of Intravenous L-Citrulline in Patients Aged 6-21 Years Old With Sickle Cell Disease Presenting to Emergency Departments in Acute Vaso-Occlusive CrisisSickle Cell Disease
NOT YET_RECRUITING120 Analytics
NCT02891837L-citrulline for Prevention of Sequelae of Acute Lung Injury in Pediatrics Undergoing Cardiopulmonary Bypass for Heart DefectsAcute Lung Injury
COMPLETED189 Analytics
NCT00335244Intravenous L-Citrulline to Treat Children Undergoing Heart Bypass SurgeryHeart Defects, Congenital
COMPLETED77 Analytics
PHASE3NOT YET_RECRUITING
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
Sickle Cell DiseaseUnlock trial analytics
PHASE3COMPLETED
L-citrulline for Prevention of Sequelae of Acute Lung Injury in Pediatrics Undergoing Cardiopulmonary Bypass for Heart Defects
Acute Lung InjuryUnlock trial analytics
PHASE3COMPLETED
Intravenous L-Citrulline to Treat Children Undergoing Heart Bypass Surgery
Heart Defects, CongenitalUnlock trial analytics

Study Endpoints

Primary Endpoints

Change in pain score from baseline to discharge
From enrollment to hospital discharge (typically within 12 to 72 hours), up to max of 30 day study duration

This outcome measures the change in self-reported pain using either the Numeric Rating Scale (NRS) or the Faces Pain Scale. Participants will rate their pain at baseline (prior to study treatment) and again at the time of hospital discharge. The pain scale used depends on the participant's age and cognitive ability. A clinically meaningful improvement is defined as a reduction of ≥2 points or ≥30% from baseline.

Time to pain crisis resolution
From start of study drug infusion to discontinuation of IV opioids (within the index hospitalization), up to max of 30 day study duration

Time (in hours) from administration of the initial bolus dose of study drug (L-citrulline or placebo) to the end of the last IV opioid dose required during the hospitalization. This endpoint reflects how quickly the participant's vaso-occlusive crisis resolves to a degree that no longer requires intravenous opioid pain medication.

A Composite Variable Consisting of the Longer of Either (1) Length of Time on Mechanical Ventilation or (2) Length of Inotrope Use.
28 Days

Mechanical ventilation (MV) = invasive or noninvasive MV incl. bilevel (biphasic) positive airway pressure or continuous positive airway pressure. Inotrope use = medications considered within the derivation of total inotrope score (dopamine, dobutamine, milrinone, epinephrine, phenylephrine, norepinephrine). Both measures recorded until earliest of subject hospital discharge or Day 28.

Duration of postoperative mechanical ventilation in hours compared between treatment groups.
Measured in hours from the end of surgery until extubation
Time to Non-invasive/Invasive Mechanical Ventilation
From the start of infusion to Day 60 Follow-up

Time in hours from the initiation of the treatment until mechanical ventilation is required, whether non-invasive (e.g., high flow nasal cannula, bilevel positive airway pressure, oxygen therapy) or invasive (i.e., requiring intubation).

Time to Non-invasive Mechanical Ventilation
From the start of infusion to Day 60 Follow-up

Time in hours from the initiation of the treatment until non-invasive mechanical ventilation is required (e.g., high flow nasal cannula, bilevel positive airway pressure, oxygen therapy) .

Time to Invasive Mechanical Ventilation
From the start of infusion to Day 60 Follow-up

Time in hours from the initiation of the treatment until intubation for invasive mechanical ventilation is required.

Systolic Blood Pressure
Day 1

Systolic blood pressure measured in mmHg

Diastolic Blood Pressure
Day 1

Diastolic blood pressure measured in mmHg

Mean Arterial Pressure
Day 1

Mean arterial pressure measured in mmHg

L-citrulline Plasma Levels
Measured in seven blood sample time points from the beginning of surgery until end of IV Citrulline Infusion; at either 48 hours postoperatively or at extubation, whichever comes first.

Citrulline Blood Levels: 1. Baseline sample in OR prior to Cardiopulmonary Bypass prior to administration of first bolus of Citrulline or Placebo 2. Immediately after Bolus 1 administered in Operating Room. 3. 30 minutes after separation from Cardiopulmonary Bypass; immediately prior to administration of Bolus 2 and start of continuous infusion of Citrulline or Placebo. 4. Six hours after after start of infusion. 5. 12 hours after start of infusion. 6. 24 hours after start of infusion. 7. 48 hours after start of infusion; or whenever infusion is discontinued if prior to 48 hours.

Secondary Endpoints

Duration of hospital stay
From study drug administration to hospital discharge (typically within 12 to 72 hours), up to max of 30 day study duration up to max of 30 day study duration
Total opioid use during hospitalization
From ED registration to hospital discharge, up to max of 30 day study duration
Proportion of patients with ≥30% reduction in opioid use
From start of study drug administration to hospital discharge, up to max of 30 day study duration
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
PlaceboPLACEBO_COMPARATORParticipants randomized to this arm will receive a placebo intravenous (IV) treatment designed to match the appearance and administration schedule of L-citrulline. The placebo will be given as a single bolus dose followed by a continuous infusion for up to 12 hours. All participants will continue to receive standard of care pain management for sickle cell disease, consistent with the treating site's protocol and adjusted as needed based on the patient's clinical condition.
L-citrulline Intravenous Treatment ArmEXPERIMENTALParticipants randomized to this arm will receive intravenous (IV) L-citrulline, a naturally occurring amino acid being investigated for its potential to treat vaso-occlusive crises (VOCs) in sickle cell disease. The study drug will be administered as a 50 mg/kg IV bolus, followed by a continuous infusion at 9 mg/kg/hour for up to 12 hours. The investigational product is provided as an isotonic solution in vials containing L-citrulline 50 mg/mL. Treatment will begin within 120 minutes of informed consent/assent and following the initial dose of opioid or ketamine, but prior to any subsequent doses. All participants will continue to receive standard-of-care (SoC) pain management per site protocol, which may be adjusted based on clinical response to study treatment.
L-citrullineEXPERIMENTAL* Bolus of 150 mg/kg at the initiation of cardiopulmonary bypass, but after removal of any crystalloid base; * Addition of study medication at a concentration of 200 μmol/L given as a bolus during bypass. This may be administered as a one-time bolus or multiple administrations to compensate for fluids containing L-citrulline that may be removed from the patient during the course of the operation and thus to maintain the concentration of 200 μmol/L; * Bolus of 20 mg/kg 30 minutes after decannulation from cardiopulmonary bypass; * 9 mg/kg/hr continuous infusion for up to 48 hours.
1EXPERIMENTALIntravenous L-citrulline
2PLACEBO_COMPARATORPlacebo of intravenous L-citrulline
IV L-Citrulline (Turnobi) ArmACTIVE_COMPARATORPatients randomized to citrulline will receive an initial intravenous bolus of 20 mg/kg (to a maximum of 1500 mg) L-citrulline over 10 minutes. The study solution will be prepared as a 5% isotonic solution (50 mg/mL) in 5% dextrose water. Immediately after the initial bolus, a continuous intravenous infusion of L-citrulline at 9 mg/kg (max 700 mg) per hour will be administered through a dedicated intravenous line or port of a multi-lumen catheter.
Placebo ArmPLACEBO_COMPARATORPatients randomized to placebo arm will receive an infusion of 5% dextrose water matched for volume and color to the citrulline infusion. The placebo infusion will consist of an initial iv bolus (up to 30 mL) over 10 minutes followed by a continuous infusion of 5% dextrose water (about 15 mL/hr). The initial bolus and subsequent infusion will be administered through a dedicated intravenous line or port of a multi-lumen catheter.
Intravenous L-CitrullineEXPERIMENTALIV bolus of 150 mg/kg L-citrulline at the initiation of bypass, followed by L-citrulline (200 μmol/L) addition to the filtration or hemoconcentration replacement fluid used during bypass. Plus L-citrulline (20 mg/kg) bolus 30 minutes after decannulation from bypass, immediately followed by 9 mg/kg/h continuous L-citrulline infusion for 48 hours.
Placebo of Intravenous L-CitrullinePLACEBO_COMPARATORPlacebo administered according to the same schedule as L-citrulline

Interventions

NameTypeDescription
L-citrullineDRUGThis intervention uses intravenous L-citrulline as an acute treatment for vaso-occlusive crisis (VOC) in sickle cell disease, administered as a 50 mg/kg IV bolus followed by a 9 mg/kg/hr continuous infusion. Unlike other studies that evaluate oral citrulline or chronic VOC prevention, this study focuses on real-time symptom resolution in the emergency department setting by targeting impaired nitric oxide production and vasoconstriction. The selected dosing regimen was optimized in prior studies to achieve a therapeutic plasma concentration associated with improved pain scores and reduced opioid use, distinguishing it mechanistically and clinically from other interventions.
PlaceboOTHERPlacebo intravenous (IV) treatment designed to match the appearance and administration schedule of L-citrulline
Placebo of intravenous L-citrullineDRUGPlacebo of intravenous L-citrulline
Intravenous L-CitrullineDRUG -
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Eligibility Criteria

Age Range6 Years to 21 Years
SexALL
Healthy VolunteersNo
Study Sites6

Inclusion Criteria: * 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 * For females of ch...

Countries:United StatesAustriaGermanyIsrael
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Frequently asked questions about L-Citrulline

What is L-Citrulline?

L-Citrulline is a small molecule therapeutic being developed by Travere Therapeutics, Inc. (TVTX) as an intravenous treatment. It is under study in acute hypoxemic respiratory failure, acute lung injury, congenital heart defects, atrial septal defect, and sickle cell disease. It is investigational and has not been approved by the FDA.

What is L-Citrulline used for in sickle cell disease?

L-Citrulline is being studied as an intravenous treatment for patients aged 6 to 21 years with sickle cell disease who present to emergency departments in acute vaso-occlusive crisis. The Phase 3 trial NCT06989567 is not yet recruiting and is planned to enroll 120 participants in the United States.

Who makes L-Citrulline?

L-Citrulline is being developed by Travere Therapeutics, Inc., which trades on the Nasdaq under the ticker TVTX. The company is the sponsor of the clinical program evaluating intravenous L-Citrulline across respiratory, cardiac, and sickle cell disease indications.

What phase is L-Citrulline in?

L-Citrulline is in Phase 2 development overall, with individual trials spanning Phase 1 through Phase 3. It is investigational and has not been approved by the FDA. The program includes one active trial, the Phase 3 sickle cell disease study NCT06989567, which is not yet recruiting.

What clinical trials is L-Citrulline in?

Registered trials include NCT06989567, a Phase 3 study in sickle cell disease vaso-occlusive crisis; NCT04570384, a completed Phase 2 study in acute hypoxemic respiratory failure in patients with COVID-19; NCT02891837, a completed Phase 3 study in pediatric acute lung injury after cardiopulmonary bypass; and NCT01120964, a completed Phase 1 study in children undergoing heart bypass surgery.

Is L-Citrulline the same as Intravenous L-Citrulline?

Yes. Intravenous L-Citrulline is another name for L-Citrulline, referring to the intravenous formulation of the small molecule. Both names refer to the same investigational asset developed by Travere Therapeutics, Inc. (TVTX) for respiratory, cardiac, and sickle cell disease indications.