Enteral L Citrulline Supplementation in Preterm Infants - Safety, Efficacy and Dosing
Phase: PHASE1
Conditions: Bronchopulmonary Dysplasia, Bronchopulmonary Dysplasia Associated Pulmonary Hypertension, Pulmonary Hypertension, Premature Birth, Chronic Lung Disease of Prematurity
Sponsor: The University of Texas Medical Branch, Galveston

 
 
 
 
 
 
 
 
Enteral L citrulline supplementation in preterm infants – safety, efficacy and dosing 
 
 
Version Number: 3 
Date: 06/02/2019 
 
 
 
PI: Amna Qasim 
RB 6, 301 University Blvd, Galveston, TX 77550 
 
Supervisor: Sunil Jain, M.D., Professor,  
Department of Pediatrics 
UTMB, Galveston  
 
 
 
 
 
 
 
 
 
 
Sub-Investigators: 
Varun Modi, Department of Pediatrics, UTMB, Galveston 
Wesam Sourour, Department of Pediatrics, UTMB, Galveston  
Maria Franco-Fuenmayor, Department of Pediatrics, UTMB, Galveston  
 
 
 
 
 
 
 
 
 

 
1 
 
 
 
 
 
 
Table of Contents: 
 
Study Schema 
1.0 
Background 
2.0 
Rationale and Specific Aims 
3.0 
Inclusion/Exclusion Criteria 
4.0 
Enrollment/Randomization 
5.0 
Study Procedures 
6.0 
Study Product Description 
7.0 
Reporting of Adverse Events or Unanticipated Problems involving Risk to 
Participants or Others 
8.0 
Study Withdrawal/Discontinuation 
9.0 
Statistical Considerations 
10.0 
Ethical Considerations and Privacy/Confidentiality Issues 
11.0 
Record Retention 
12.0 
References 
 
 
 
 

 
2 
SIGNATURE PAGE 
The signature below constitutes the approval of this protocol and the attachments, and 
provides the necessary assurances that this trial will be conducted according to all 
stipulations of the protocol, including all statements regarding confidentiality, and 
according to local legal and regulatory requirements and applicable US federal 
regulations and ICH guidelines. 
 
Site Investigator: * 
 
Signed: 
Snigdha Bhatia, M.D.  
Date: 
06/02/2019 
 
Name 
Title 
 
 
 
* The protocol should be signed by the local investigator who is responsible for the study 
implementation at his/her specific site; i.e., if Investigational New Drug study, the 
individual who signs the Form FDA 1572. 

 
3 
1.0 
Background 
 
Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in preterm 
infants (PI).  BPD is defined as requirement for additional oxygen at 36 weeks corrected 
gestational age (CGA) in infants born with a birth weight < 1500 g and GA < 32 weeks. 
Pulmonary hypertension (PH) develops in 25-37% of patients with BPD and is associated 
with significant morbidity/mortality(1).Multiple factors contribute to the development 
of BPD associated PH (BPD_PH). Preterm birth causes disruption in pulmonary vascular 
growth that leads to decreased vascular surface area that increases pulmonary vascular 
resistance (PVR).  Increased PVR leads to altered vasoreactivity and structural 
remodeling with intimal hyperplasia and increased muscularization of the small 
pulmonary arteries. There is no definite treatment for BPD_PH.  
 
Nitric Oxide: Nitric Oxide (NO) is a potent pulmonary vasodilator. Endothelial Nitric 
oxide synthase (eNOS) mediates production of NO from L-Arginine. L-citrulline is a 
precursor for L-arginine. L-Arginine is a precursor of nitric oxide (NO). Nitric oxide (NO) is 
produced in the pulmonary arterial endothelial cells (PAECs) from L-arginine by an 
enzyme endothelial nitric oxide synthase (eNOS). NO is a signaling molecule which leads 
to dilatation of lung blood vessels and decreases pulmonary vascular resistance, leading 
to decreased pulmonary hypertension. L-citrulline is an end-product of this reaction and 
it recycles back to form L-arginine via a two-step enzymatic pathway (figure 1) involving 
arginosuccinate synthase (ASS) and arginosuccinate lyase (ASL).  
 
Arginine and citrulline in infants with BPD_PH: In infants with BPD_PH, there are 
decreased levels of L-arginine & L-citrulline with decreased production of NO (measured 
by urinary nitrates & nitrites) leading to increased pulmonary vascular resistance. It is 
suspected that genetic variations in enzymes involving citrulline synthesis may 
contribute to the susceptibility to develop pulmonary hypertension(2). A cross-sectional 
pilot study by Montgomery et al reported that L-citrulline levels < 29 µmol/L predicted 
BPD_PH with 100% sensitivity and 75% specificity(3).   
 
Supplementation of citrulline and PVR: Fike et al showed that oral supplementation  
with L-citrulline increases vascular NO production and attenuates the development of 
elevated pulmonary vascular resistance (PVR) in a newborn piglet model of chronic-
hypoxia induced pulmonary hypertension(4). In a newborn rat model of hypoxia-
induced BPD, subcutaneous injection of L-citrulline decreased pulmonary vascular 
remodeling and reduced right ventricular hypertrophy (both of these are markers of 
pulmonary hypertension)(5). A Phase 2 clinical trial of L-citrulline in pediatric patients 
with sickle cell disease showed decreased vascular complications and improvement in 
overall well-being(6). L-citrulline has been used in post cardio-pulmonary bypass 
patients and it has been shown that post-operative pulmonary hypertension did not 
develop in children who had naturally elevated citrulline levels or who achieved plasma 
levels greater than 37 µmol/L with oral citrulline supplementation(7).  
 

 
4 
 
Figure 1. Urea cycle. Adapted from American Journal of Physiology, March 2015.  
 
Why oral L-citrulline: In in-vitro studies, L-arginine promotes NO production (See Figure 
1) but in in-vivo studies (animal models of PH), oral L-arginine did not increase NO 
production due to hydrolysis of L-arginine by arginases present in enterocytes in 
gastrointestinal tract and hepatocytes, leading to decreased bioavailability of oral L-
arginine. Alternatively, oral L-citrulline (precursor for L-arginine figure 1) can be used to 
increase L-arginine & NO production.  After being produced and released into the 
circulation by enterocytes, L-citrulline passes through the liver without major 
metabolism. Cells in the proximal tubules of the kidney take up and metabolize some of 
the circulating L-citrulline into L-arginine in urea cycle via enzymes arginosuccinate 
synthase and arginosuccinate lyase. Therefore, a significant portion of the L-citrulline 
produced by enterocytes reaches the systemic circulation as compared to L-arginine. 
PAECs express the enzymes ASS and ASL and can use L-citrulline to produce NO. There is 
some evidence suggesting that co-localization of these enzymes with eNOS in the 
plasmalemmal caveolae (invaginations of plasma membrane in the pulmonary arterial 
endothelial cells) may allow L-citrulline-induced increases in L-arginine to be directly 
channeled to eNOS rather than equilibrating with intracellular levels(2). 
 
In-vitro and In-vivo studies of L-citrulline supplementation in newborn piglets showed 
increased NO production and decreased PH in newborn piglets. These studies also 
showed that treatment with L-citrulline reduced superoxide generation, increased NO 
production as well as helped with eNOS re-coupling which is the active form of eNOS 
(dimeric form of eNOS is the active form).  
 
Arginine as essential amino acid: Under routine conditions arginine is not an essential 
amino acid but is considered an essential amino acid in neonates, particularly under 
stress, infection and prematurity.  In neonatal period (suckling period), the major source 
for endogenous arginine biosynthesis is from citrulline in the intestine.   

 
5 
Source of L-arginine in preterm infants: Routinely, extremely premature infants receive 
nutrition as total parental nutrition (TPN i.e. infants get infusion of protein, fat and 
carbohydrate via central venous line) that contains L-arginine (approximately 1mg/1mL) 
to metabolize ammonia via urea cycle. PIs receive adequate amount of intra venous 
arginine from TPN.   Routinely, PIs are started with small volumes of enteral feeds which 
are increased slowly overtime. TPN is slowly decreased as enteral feeds are increasing. 
As the TPN is going down, intra venous L-arginine intake also drops down and ultimately 
when the PI are off TPN, they don’t get any IV supplemental L-arginine.   
Why long term IV arginine not possible in preterm infants: In PI, the major cause of 
late onset infection (after 7 days of age) is central line related infection that is why 
central line is taken out as soon as infant reaches full feed.  
Why oral citrulline: Enteral feeds (formula as well as breast milk) is poor source of 
arginine. Once PIs are on full enteral feed, an enteral feed is the only source of arginine. 
Interestingly, 40% of enteral arginine gets metabolized by arginase enzyme present in 
intestine. We speculate that plasma levels of arginine drop once TPN is discontinued 
and infants are on full feeds. Oral L-arginine has poor bio-availability that is why oral L-
arginine supplementation does not increase blood levels of arginine. Since oral citrulline 
has high bioavailability, the best way to increase serum arginine levels is by oral 
citrulline supplementation.  Oral supplementation of L-citrulline in preterm infants 
once they are off TPN will likely to increase arginine levels and NO production.  
 
Safety of oral citrulline: L-citrulline has been safely used for decades in patients with 
urea cycle defects. It has been used in pediatric patients with sickle cell disease and in 
infants undergoing cardiac surgery. No side effects were reported in these studies. In a 
study in newborn rats exposed to hyperoxia, L-citrulline caused a marked increase in 
arginase-2 expression in the lungs and this could have an impact on lung development 
and remodeling(5). However, this is only a theoretical risk.  
 
Oral L-citrulline supplementation may prevent and/or decrease the severity of BPD_PH. 
Since oral L-citrulline supplementation has never been studied in preterm infants 
before, the side effect profile and appropriate dosing is still unknown. In this pilot 
study, we will determine the safety profile, efficacy and appropriate dosing of oral L-
citrulline in preterm infants. In future, information from this study will be utilized to 
conduct a randomized placebo-controlled trial to evaluate the role of L-citrulline 
supplementation in treating BPD_PH.  
 
 
 
 
 
 
 
 
 

 
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2.0 
Rationale and Specific Aims 
 
 
Specific Aim 1 -  
To test the hypothesis that enteral supplementation of L-citrulline (a precursor of L-
arginine) is effective in increasing plasma L-arginine and L-citrulline concentrations in 
premature infants with increased NO production.  
 
Intervention: Enteral L-citrulline supplementation 
 
Rationale & feasibility - L-arginine is a precursor of NO production. Premature infants 
who develop BPD_PH have lower levels of L-arginine and L-citrulline, decreased NO 
production, eventually leading to the development of pulmonary hypertension. Oral 
arginine is poorly bioavailable hence oral L-citrulline will be used (precursor of L-
arginine, see figure below). We expect L-citrulline supplementation in premature infants 
will increase plasma L-arginine and L-citrulline concentrations and increase NO 
production (measured indirectly by urinary end-products).   
 
Specific Aim 2 -  
To determine the safety of oral L-citrulline supplementation in premature infants.  
Increased production of NO may lead to systemic hypotension by its vasodilator effect. 
All infants in the neonatal ICU are always on electronic monitors and monitored for 
heart rate, oxygen saturations and BP. We will continuously monitor all infants for 
systemic hypotension. Significant hypotension will be defined as a 25% drop in systemic 
mean blood pressure (measure by non-invasive blood pressure monitoring). Other 
parameters to be recorded include increase in oxygen requirements/escalation in 
respiratory support, metabolic abnormalities (on routine glucoses and electrolyte 
monitoring), effect on bone-marrow by weekly complete blood counts (done routinely 
on preterm infants).  
 
Specific Aim 3 – 
To determine the dose of enteral L-citrulline required to increase plasma level of > 37 
µmol/L. 
We will use three doses (low, medium and high) of enteral L-citrulline as follows -  
Group 1: Low dose 50 mg/kg given two times a day (100 mg/kg/day) for total 7 days.   
Group 2: Medium dose 100 mg/kg given two times a day (200 mg/kg/day) for total 7 
days 
Group 3: High dose 150 mg/kg given two times a day (300 mg/kg/day) for total 7 days 
 
Rationale:  

 
7 
Previous studies in patients undergoing cardiac surgery have shown that post-operative 
pulmonary hypertension did not develop in patients with citrulline level > 37 µmol/L(7). 
A cross-sectional study reported that citrulline levels < 29 µmol/L was associated with 
BPD_PH (100% sensitivity and 75% specificity) hence this may be used as a screening 
tool for BPD_PH(3). We will use the higher levels of citrulline of the reported levels as 
our goal (>37µmol/L). We will supplement infants with 3 different dosages and check 
serum levels to see what dose is required for to achieve optimal plasma level of 
citrulline (>37µmol/L).  
 
 
 
3.0 
Inclusion/Exclusion Criteria 
 
Inclusion criteria - Subjects must meet all of the inclusion criteria in order to be eligible 
to participate in the study. 
1. Infants £ 30 weeks’ gestational age born at UTMB, Galveston. 
2. Parents have provided informed consent/assent in a manner that is approved by the 
IRB  
 
The reason for the inclusion of such a vulnerable population is that BPD is primarily a 
disease of premature infants and PH is a common complication of BPD. It is also a 
condition with high mortality and there still exists significant confusion over appropriate 
management. Being a randomized controlled trial, the study does add certain risks to 
the subjects: frequent blood draws (minimized by using discarded blood and urine 
samples) . Since diagnosis and management of BPD_PH is not currently standard of 
practice, we will not be withholding any beneficial therapy. The present research 
protocol will not interfere in the management of the preterm infants as treating 
neonatal team will be taking all management decisions. All risks will be explained to the 
parents and written informed consent will be obtained from the parents of all subjects.  
 
Exclusion criteria - Subjects meeting any of the exclusion criteria at baseline will be 
excluded from study participation. 
 
1. Known congenital or chromosomal anomalies.  
2. Congenital heart disease affecting cardio-respiratory system (other than PDA, PFO or 
ASD) 
3. NEC, sepsis, or any condition requiring surgery prior to recruitment  
 
 
 
 
 
 
 

 
8 
 
 
4.0 
Treatment Assignment/Randomization 
 
Recruitment - Parents of all eligible infants will be approached by research investigator 
to discuss about the study & research protocol in detail. All questions & concerns will be 
answered in very simple language & parents will be given written consent form to read. 
Within 24 to 48 hours, the parents will be approached again to discuss & explain any 
question they have. We expect around 70 - 75% success in the recruitment. Every year, 
we deliver around 50 infants (<30 weeks’ gestation). We hope to recruit our desired 
sample of 42 infants (14 in each study group) within 12 months.  
 
Sample size: 14 preterm infants will be randomized to each group (total sample 42) 
A sample size of 14 at each group (low, median, and high dose) for efficacy endpoint will 
reach a power of 0.80 to detect an effect size of 0.5 based on one-way ANOVA with a 
0.05 significance level. A sample size of 11 at each group for safety endpoint will reach a 
power of 0.92 at a 0.05 significant level for an equivalence test of means using two one-
sided tests, when the true difference between the means is 0.0 mmHg, the standard 
deviation is 10.0 mmHg, and the equivalence limits are -15.0 mm Hg and 15.0 mmHg. 
 
Randomization: Adaptive randomization method will be used – each new participant 
will be sequentially assigned to a particular treatment group by taking into account the 
previous assignments of participants. For example, first recruit will be Group 1, second 
Group 2, third Group 3, fourth Group 1 and so on. The study will be blinded to the 
nurses and parents. If patients complete 12/14 doses of the treatment, they will be 
analyzed in the treatment arm.  
 
Study groups –  
Group 1: Low dose 50 mg/kg given two times a day for a total of 7 days (100 mg/kg/day) 
Group 2: Medium dose 100 mg/kg given two times a day for a total of 7 days (200 
mg/kg/day)  
Group 3: High dose 150 mg/kg given two times a day for a total of 7 days (300 
mg/kg/day) 
 
 
Justification for dosing: Pharmacokinetic studies show that half-life of IV citrulline is 60 
minutes(8). Half-life of enteral Citrulline has not been studied but previous studies by 
Montogemery et al, Schwedhelm et al and Waugh et al reported efficacy with twice 
daily dosing(3, 6, 9). We will also use twice daily dosing. The actual dosing used in 
previous studies were 80 mg/kg twice daily and 100 mg/kg twice daily respectively. 
Study in newborn piglets shows that higher doses are associated with greater efficacy. 
We will use three different dose ranges to determine efficacy (i.e. plasma citrulline level 
> 37 µmol/L. increase in plasma arginine levels and urinary nitrites/nitrates).  

 
9 
 
 
 
 
 
 
5.0 
Study Procedures 
 
Data collection - Antenatal, delivery & post-natal (after birth), all detailed data will be 
collected from electronic medical records (EMR) by the investigators & saved in a 
password protected computer. We will calculate SNAPPE 2 (Score for Neonatal Acute 
Physiology – Perinatal Extension 2 – a 9 point validated scoring system that predicts 
neonatal mortality(10)) for all subjects to ensure equal distribution of sick infants.  
 
Study drug – Oral/enteral L-Citrulline as 10 % solution (100 mg/ml) will be provided to 
the bedside nurse by the Investigational Pediatric Pharmacy. The drug will be given via 
gavage feeding by bolus infusions followed by a 0.5 ml water flush twice daily (1200 and 
0000). Bolus dosing will be needed due to the small volumes (0.5–1.5 ml per dose in 
most infants). The volume of nasogastric tubing used in preterm infants (Ameritus 4.0 Fr 
50 cm) is 0.48 ml, therefore we will follow the administration with 0.5 ml of saline/water 
flush to ensure all the study drug is delivered to the patient. 
 
Dispensing study drug - After enrollment & randomization, the research nurse will 
inform the pharmacy about randomization group. A 10% solution of L-citrulline will be 
prepared to administer 50 mg/kg, 100 mg/kg and 150 mg/kg doses for Groups 1,2 and 3 
respectively. The shelf life of dispensed L-citrulline is 24 hours. L-citrulline will be 
dispensed as a single dose twice daily for each subject.  
 
Administration of study drug - Will be given via gavage feeding tube twice daily (1200 ± 
30 mins, 0000 ± 30 mins). The time of 0000 will be in the window of citrulline’s peak 
serum levels at 5-8 hours when routine blood collection is done at 0400(11). L-citrulline 
will be given by the bedside nurse as a bolus followed by 0.5 ml water flush. L-citrulline 
will be given separate from feeds to avoid any confusion.  
 
Dose of study drug –  
Low dose 100 mg/kg/day 
Medium dose 200 mg/kg/day  
High dose 300 mg/kg/day 
 
When to start study drug - Study drug will be started when infant has been off of TPN 
for at least 3 days so that IV arginine in TPN does not interfere.  
 
Sample collection - 1 mL of blood will be collected from each subject at 2 time points: 
before starting citrulline (Day 0) and then after completing 1 week enteral L-citrulline 
supplementation (Day 7). Discarded blood sample from routine blood draw will be used. 

 
10 
It is standard of care for all preterm infants to get weekly blood draws on Tuesdays for 
hemoglobin monitoring. We will use discarded blood sample from the Tuesday after 
being on full feeds (no TPN) and start enteral L-citrulline supplementation on the first 
Tuesday (Day 1) after off TPN for at least 3 days. After 1 week, supplementation will be 
discontinued (last dose Monday PM) and discarded blood sample from Tuesday (Day 7) 
will be used to analyze plasma levels or L-citrulline and L-arginine.  
Immediately after blood collection, blood will be centrifuged at 4-degree C to extract 
serum. Serum will be divided into aliquots of 100 microliter & stored at -80-degree C for 
future use.  
 
1 mL of urine will be collected before starting (Day 0) and then daily thereafter till the 
last day of L-citrulline supplementation (Day 7). Urine will be collected by placing cotton 
balls in diapers at around noon ± 2 hours (in between the 2 doses of study drug).  
 
All sample collection will be part of routine/standard care of the infant and no extra 
blood draws/invasive procedures will be needed.  
 
 
 
Measurements: 
 

 
11 
Serum L-citrulline & L-arginine measurement - We will measure amino acids (AA) in 
serum using an HPLC-MS approach. A cocktail of stable-isotope enriched AA will be 
added to serum samples & AA will be extracted using a solid-phase cartridge. Extracted 
AA will be separated by HPLC (C-18 Colum) eluted with a methanol ammonium formate 
gradient. AA will be injected directly into a QTRAP 6500 instrument tuned for low mass 
analyses. AA will be detected using characteristic fragmentation ions. Concentrations of 
AA in the original sample will be determined by co-paring peak areas to those of the 
stable isotope-enriched internal standards. For this initial study, we will measure 
citrulline & arginine.  
 
Urinary nitrates and nitrite measurement (metabolites of NO) - Urinary nitrite, nitrate 
and creatinine will be measured by GC-MS following conversion to the 
pentafluorobenzyl derivatives. 
 
 
 
6.0 
Study Product Description 
Information in this section can usually be obtained from the IB or the package insert.  
Formulation, Packaging, and Labeling 
Product Storage and Stability 
Keep container dry. Keep in a cool place. Ground all equipment containing material. 
Keep container tightly closed. Keep in a cool, well-ventilated place. Combustible 
materials should be stored away from extreme heat and away from strong oxidizing 
agents. 
 
Precautions: Keep away from heat. Keep away from sources of ignition. Empty 
containers pose a fire risk, evaporate the residue under a fume hood. Ground all 
equipment containing material. Do not breathe dust. Wear suitable protective clothing 
in case of insufficient ventilation, wear suitable respiratory equipment If you feel unwell, 
seek medical attention and show the label when possible. Avoid contact with skin and 
eyes 
 
 
 
Dosage, Preparation and Administration of Study Intervention/Investigational Product 
 
A 10% L-citrulline solution will be prepared using the powdered product by adding 10 g 
of powder in 100 ml of distilled water (each ml = 100 mg). Doses prepared will be 
determined by the study group assignment. For e.g., for a 2 Kg infant in Group 1 (50 
mg/kg dose = 1 ml). Doses will be administered twice daily. 
 

 
12 
Safety precautions: Gloves Splash goggles, lab coats, dust respirators and gloves should 
be used while preparing the doses. Avoid direct contact with skin. Prepared solutions 
can be held in a cool place for a maximum of 24 hours.  
 
 
 
 
Modification of Study Intervention/Investigational Product for a Participant 
 
No dose modifications will be done for specific lab values. In case of toxicity, study will 
be aborted as discussed in section 7.0 below.  
 
 
Accountability Procedures for the Study Intervention/Investigational Product(s) 
 
Study drug (L-citrulline) will be bought from the vendor (Vitaflo) by the PI. The product 
will be shipped at one time. About 300 g of product will be needed for this study. 
Unused product will be in the investigational pharmacy for future studies.  
 
Assessment of Subject Compliance with Study Intervention/Investigational Product  
  
Since all doses will directly be administered by the bedside nurse, non-compliance is not 
applicable to this study. Subjects must receive 12/14 doses to be considered a complete 
subject.  
 
 
Concomitant Medications/Treatments 
 
 
There will be no medication or treatment restrictions during this study. All premature 
infants will continue to receive standard of care treatment.  
 
7.0 
Adverse Events or Unanticipated Problems involving Risk to Participants or 
Others 
 
Immediate risks: Increased NO production may theoretically lead to systemic 
hypotension – all these infants will be in an intensive care setting with cardiac monitors 
and continuous blood pressure monitoring.  Significant hypotension will be defined as a 
25% drop in systemic mean blood pressure from baseline (average mean arterial 
pressure in the week prior to starting study drug). 
Local irritation to skin or eyes is possible with direct contact with study drug.  
 

 
13 
Long-range risks: A theoretical risk of adverse impact on structural remodeling of 
pulmonary architecture vis increase in arginase two expression in lungs (seen in rats).  
 
Rationale:  
Children with urea cycle defects have been treated with L-citrulline for decades and 
showed no evidence of toxicity. Previous studies in literature have not reported any 
significant adverse effects. The benefit of treatment (helping treat or prevent BPD_PH) 
far outweighs the risks since this condition is associated with significant 
morbidity/mortality and no preventative measures exist at this time. The study drug has 
already been tested on animal models and there are no alternatives to studying the 
safety, efficacy and dosing in preterm infants.  
 
 
ICH E6 defines an AE as any untoward medical occurrence in a patient or clinical 
investigation subject administered a pharmaceutical product regardless of its causal 
relationship to the study treatment. An AE can therefore be any unfavorable and 
unintended sign (including an abnormal laboratory finding), symptom, or disease 
temporally associated with the use of medicinal (investigational) product.  
 
All AEs including local and systemic reactions not meeting the criteria for “serious 
adverse events” should be captured on the appropriate CRF. Information to be collected 
includes event description, time of onset, clinician’s assessment of severity, relationship 
to study product (assessed only by those with the training and authority to make a 
diagnosis, which would include MD, PA, Nurse Practitioner, DO, or DDS), and time of 
resolution/stabilization of the event. All AEs occurring while on study must be 
documented appropriately regardless of relationship. All AEs will be followed to 
adequate resolution.  
 
Any medical condition that is present at the time that the patient is screened will be 
considered as baseline and will not be reported as an AE. However, if it deteriorates at 
any time during the study, it should be recorded as an AE. 
 
All AEs must be graded for severity and relationship to study product.  
 
Severity of Event:  All AEs will be assessed by the clinician using a protocol defined 
grading system. For events not included in the protocol defined grading system, then 
the following guidelines will be used to quantify intensity.  
• 
Mild: events require minimal or no treatment and do not interfere with the patient’s 
daily activities. 
• 
Moderate: events result in a low level of inconvenience or concern with the 
therapeutic measures. Moderate events may cause some interference with 
functioning. 

 
14 
• 
Severe: events interrupt a patient’s usual daily activity and may require systemic 
drug therapy or other treatment. Severe events are usually incapacitating. 
• 
Life threatening:  any adverse drug experience that places the patient or subject, in 
the view of the investigator, at immediate risk of death from the reaction as it 
occurred, i.e., it does not include a reaction that had it occurred in a more severe 
form, might have caused death. 
 
Changes in the severity of an AE should be documented to allow an assessment of the 
duration of the event at each level of intensity to be performed. Adverse events 
characterized as intermittent require documentation of onset and duration of each 
episode. 
 
Protocol Grading System for Hypotension: 
 
Mild: Drop in systemic mean arterial pressure (MAP) £ 10% from baseline  
 
Moderate: Drop in systemic mean arterial pressure (MAP) £ 25% from baseline  
 
Severe: Drop in mean arterial pressure (MAP) > 25% from baseline  
 
Life threatening: Severe hypotension requiring 2 or more inotropes (Dopamine, 
Epinephrine, Norepinephrine) 
 
Relationship to Study Products: If there is any doubt as to whether a clinical 
observation is an AE, the event will be reported. All AEs must have their relationship to 
study product assessed using the terms: associated or not associated. In a clinical trial, 
the study product must always be suspect. To help assess, the following guidelines are 
used. 
• Associated – The event is temporally related to the administration of the study 
product and no other etiology explains the event. 
• Not Associated – The event is temporally independent of study product and/or the 
event appears to be explained by another etiology. 
 
Serious Adverse Event (SAE): An SAE in our study will be defined as an AE that meets 
one of the following conditions: 
• 
Death during the period of protocol defined surveillance 
• 
Life-threatening event (defined as a subject at immediate risk of death at the time of 
the event) – significant hypotension requiring 2 or more inotropes 

 
15 
• 
Results in a persistent or significant disability/incapacity: Intraventricular 
hemorrhage Grade III or more, Necrotizing enterocolitis requiring surgery, 
Retinopathy of prematurity requiring surgery  
• 
Significant lab abnormalities: Thrombocytopenia < 50,000 
 
All SAEs will be: 
• 
recorded on the appropriate SAE CRF 
• 
followed through resolution by a study clinician 
• 
reviewed and evaluated by a study clinician 
 
A DSMB (data safety monitor board). DSMB will review data (from CRFs) every 3 months 
to make sure it is safe to give citrulline to preterm infants.  
DSMB will have -  
1. Dr. Joan Richardson MD, Neonatologist, Prof and Chief of Neonatal Division, UTMB  
2. Dr. Ashraf Aly MD, PhD, Pediatric Cardiologist, Prof Department of Pediatrics, UTMB  
3. Dr. Maged Costantine MD, Maternal Fetal Medicine, Associate Prof, Department of 
ObGyn, UTMB 
4. Dr. Karen Smith PhD, Pediatric Psychologist, Prof Department of Pediatrics  
 
 
Procedures to be Followed in the Event of Abnormal Laboratory Test Values or 
Abnormal Clinical Findings 
 
Reporting Procedures 
 
Discarded blood samples from routine blood draws will be used for study 
measurements. No extra blood will be drawn from infants. This study does not involve 
any invasive procedures. 
 
Any AE considered serious by the PI or Sub investigator or which meets the 
aforementioned criteria must be submitted on the SAE form to the IRB in accordance 
with IRB policies and procedures. 
 
 
The study clinician will complete a Reportable Event Form within the following 
timelines:   
 

 
16 
• 
All serious adverse events described above to the UTMB IRB will be reported via 
InfoED utilizing the Reportable Event Form within 10 days. 
• 
Serious adverse events involving an unexpected death or life-threatening experience 
related to research which be reported to the UTMB IRB within 2 days after first 
knowledge by the principal investigator.  
 
All SAEs will be followed until satisfactory resolution or until the PI or Sub investigator 
deems the event to be chronic or the patient to be stable.  
 
 
 
 
 
 
 
 
 
8.0 
Study Withdrawal/Discontinuation 
 
Reasons for Withdrawal 
 
A study subject will be discontinued from participation in the study if any of the 
following occur: 
• Unacceptable toxicity or adverse event (AE): Drop in systemic mean blood 
pressure > 25% from baseline  
• Unacceptable laboratory abnormalities: Thrombocytopenia < 50,000 not 
explained by other co-existing conditions 
• Intercurrent illness, or other medical condition or situation occurs such that 
continued participation in the study would not be in the best interest of the 
subject in the opinion of the treating investigator, for e.g. necrotizing 
enterocolitis requiring subject to be made NPO.  
• Development of any exclusion criteria  
• Parents withdraw consent to continue in the research for any reason 
 

 
17 
 
Handling of Withdrawals 
 
Any subjects that withdraw from the study will continue to receive standard of care 
treatment according to our NICU protocols and will continue to be followed clinically by 
the primary neonatologist. Safety data from these subjects will be presented to the 
DSMB for evaluation.  
 
Since this is a pilot study, we will not need to replace subjects in case of withdrawals.  
 
 
 
 
 
Termination of Study  
 
Given the short duration of the trial, we do not plan to conduct any interim analyses or 
specify any early-stopping rules.  
 
 
9.0 
Statistical Considerations 
 
Study design: Single-center Pilot dose-ranging study  
 
Study population: Premature infants admitted to the Neonatal intensive care unit at 
UTMB, Galveston.  
 
Rationale: L-citrulline has been shown to increase NO production in neonatal pigs. The 
use of L-citrulline in premature infants may help increase NO and prevent pulmonary 
hypertension that develops due to chronic lung disease. Even though L-citrulline has 
been used safely in infants and children for urea cycle disorders, its dosage, efficacy and 
safety have not been evaluated in premature infants. Therefore, a pilot dose-ranging 
study is essential.  
 
There will be 3 study groups in this Phase I trial: 
 
Group 1 (Low dose): 100 mg/kg/day of L-citrulline 
Group 2 (Medium dose): 200 mg/kg/day of L-citrulline  
Group 3 (High dose): 300 mg/kg/day of L-citrulline  
 
Sample size: A sample size of 14 at each group (low, median, and high dose) for efficacy 
endpoint will reach a power of 0.80 to 

 
18 
detect an effect size of 0.5 based on one-way analysis of variance (ANOVA) with a 0.05 
significance level. The sample size calculation was based on the following expected 
mean ± SD citrulline concentrations in plasma according to the study from Schwedhelm 
et al: 
Low dose group: 19 ± 4 µmol/L 
Medium dose group: 21 ± 4 µmol/L 
High dose group: 45 ± 5 µmol/L 
 
 
Primary outcome: 
 
1. 
Increase in plasma L-citrulline levels and increased NO production 
(measured indirectly via urinary breakdown products) 
 
Secondary outcomes: 
 
1. To determine safety of enteral L-citrulline supplementation in premature infants. 
 
2. To determine the dose of enteral L-citrulline needed to increase plasma level of 
citrulline > 37 mol/L. 
 
 
 
Data will be collected from electronic medical records. Measurements will be recorded 
in a password protected computer on an excel sheet.  
 
A Data Safety Monitor Board (DSMB) as mentioned in section 7.0 will be reviewing 
safety data every 4 months.  
 
The data will be analyzed at the end of data collection for all subjects who meet the 
inclusion criteria. SPSS version 24 will be used for data analysis. SAS procedures, linear 
models, repeated measures analysis of variance (ANOVA) & logistic modeling for 
receiver operator curve generation (significance p<0.05) will be used. The UTMB Clinical 
trials studio will be involved to assist in statistics.  
 
Procedure for accounting for any missing, unused and spurious data: 
 
In this pilot study, subjects with missing data on important predictors (lack of blood 
sample for serum arginine/citrulline levels) will be excluded from analyses.  
 
Selection of subjects to be included in the analyses: 
 
We will follow an intention-to-treat approach in the analyses. The primary variables 
(plasma arginine, citrulline levels and urinary nitrite, nitrate levels) are continuous data 

 
19 
and the one-way ANOVA will be used to analyze differences amongst the 3 treatment 
groups from day 0 and day 7. Paired T-test will be used to evaluate differences pre-and 
post-treatment in individual subjects. The data gathered from daily urinary nitrite and 
nitrate measurements will be represented in line graphs to represent the trend.  
 
 
 
 
 
 
10.0 
Ethics and the Protection of Human Subjects 
The investigator will ensure that this study is conducted in full conformity with the 
principles set forth in The Belmont Report: Ethical Principles and Guidelines for the 
Protection of Human Subjects of Research of the US National Commission for the 
Protection of Human Subjects of Biomedical and Behavioral Research (April 18, 1979) 
and codified in 45 CFR Part 46 and/or the ICH E6; 62 Federal Regulations 25691 (1997).   
The investigator must provide for the review and approval of this protocol and the 
associated informed consent/parental assent documents and recruitment material by 
an appropriate independent ethics committee (IEC) or IRB registered with the OHRP. 
Any amendments to the protocol or consent materials must also be approved before 
they are placed into use. In the United States and in other countries, only institutions 
holding a current US Federalwide Assurance issued by OHRP may participate. 
Informed consent is a process that is initiated prior to the individual’s (in this case, the 
legal guardians) agreeing to participate in the study and continuing throughout the 
individual’s study participation. Extensive discussion of risks and possible benefits of this 
therapy will be provided to the parents/legal guardians of the study subjects. Assent 
forms describing in detail the study interventions/products, study procedures, and risks 
are given to the subject and written documentation of informed consent is required 
prior to starting intervention/administering study product. Assent forms will be IRB-
approved and the parents will be asked to read and review the document. Upon 
reviewing the document, the investigator will explain the research study to the parents 
and answer any questions that may arise. The parents will sign the informed assent 
document prior to any procedures being done specifically for the study. The parents 
should have the opportunity to discuss the study with their surrogates or think about it 
prior to agreeing to participate. The parents may withdraw consent at any time 
throughout the course of the trial. A copy of the informed consent document will be 
given to the subjects for their records. The rights and welfare of the subjects will be 

 
20 
protected by emphasizing to the parents that the quality of their medical care will not 
be adversely affected if they decline to participate in this study. 
 
 
Privacy/Confidentiality Issues 
 
Subject confidentiality is strictly held in trust by the participating investigators, their 
staff, and the sponsor(s) and their agents. This confidentiality is extended to cover 
testing of biological samples and genetic tests in addition to the clinical information 
relating to participating subjects. 
 
The study protocol, documentation, data, and all other information generated will be 
held in strict confidence. No information concerning the study or the data will be 
released to any unauthorized third party without prior written approval of the Principal 
investigator. 
 
Individuals authorized to view study records will be identified to the study subject on 
the informed consent but may include a study monitor or other authorized 
representatives of the sponsor or funding agency or federal or local agencies that 
regulate research including representatives from the Food and Drug Administration, 
Office of Human Research Protections, or the Institutional Review Board.  Study records 
may also be made available for internal compliance reviews and quality assurance 
representatives. 
These individuals may inspect all documents and records required to be maintained by 
the investigator, including but not limited to, medical records (office, clinic, or hospital) 
and pharmacy records for the subjects in this study. The clinical study site will permit 
access to such records. 
 
In accordance with the Food and Drug Administration Amendment Act of 2007 (FDAAA) 
and The International Committee of Medical Journal Editors (ICMJE) member journals 
trials-registration policy as a condition for publication, this study will be registered in the 
public trials registry ClinicalTrials.gov, which is sponsored by the National Library of 
Medicine.  Results will be published to clinicalTrial.gov when available but will not 
identify individual subjects. 
 
 
 
11.0 
Record Retention 
 
The expected duration of this study is 1 year,  
 
Since this research study accesses protected health information (PHI) and is covered 
under the Health Insurance Portability Accountability Act (HIPAA), consent forms that 

 
21 
include the HIPAA Authorization are to be retained for a minimum of 6 years from the 
date of the authorization.  
 
Since this Research involves pediatric subjects, records shall be maintained until the last 
participating subject reaches age 21 or 10 years after completion of the research, 
whichever is later. 
 
Research records will be maintained in accordance with the current version of the Texas 
Health Records Table 17-III Record Retention Schedule, Human Subject Research 
Records and Documents.   
 
 
12.0 
References 
 
References: 
 
 
1. 
Abman SH, Hansmann G, Archer SL, Ivy DD, Adatia I, Chung WK, et al. 
Pediatric Pulmonary Hypertension Guidelines From the American Heart Association and 
American Thoracic Society. Circulation. 2015;132(21):2037-99. 
2. 
Fike CD, Summar M, Aschner JL. L-citrulline provides a novel strategy for 
treating chronic pulmonary hypertension in newborn infants. Acta Paediatrica. 
2014;103(10):1019-26. 
3. 
Montgomery AM, Bazzy-Asaad A, Asnes JD, Bizzarro MJ, Ehrenkranz RA, 
Weismann CG. Biochemical Screening for Pulmonary Hypertension in Preterm Infants 
with Bronchopulmonary Dysplasia. Neonatology. 2016;109(3):190-4. 
4. 
Fike CD, Dikalova A, Kaplowitz MR, Cunningham G, Summar M, Aschner JL. 
Rescue Treatment with L-Citrulline Inhibits Hypoxia-Induced Pulmonary Hypertension 
in Newborn Pigs. American Journal of Respiratory Cell and Molecular Biology. 
2015;53(2):255-64. 
5. 
Vadivel A, Aschner JL, Rey-Parra GJ, Magarik J, Zeng H, Summar M, et al. L-
Citrulline Attenuates Arrested Alveolar Growth and Pulmonary Hypertension in Oxygen-
Induced Lung Injury in Newborn Rats. Pediatric Research. 2010;68(6):519-25. 
6. 
Waugh WH, Daeschner CW, Files BA, McConnell ME, Strandjord SE. Oral 
citrulline as arginine precursor may be beneficial in sickle cell disease: Early phase two 
results. Journal of the National Medical Association. 2001;93(10):363-71. 
7. 
Smith HAB, Canter JA, Christian KG, Drinkwater DC, Scholl FG, Christman 
BW, et al. Nitric oxide precursors and congenital heart surgery: A randomized controlled 
trial of oral citrulline. Journal of Thoracic and Cardiovascular Surgery. 2006;132(1):58-
65. 
8. 
Barr FE, Tirona RG, Taylor MB, Rice G, Arnold J, Cunningham G, et al. 
Pharmacokinetics and safety of intravenously administered citrulline in children 
undergoing congenital heart surgery: Potential therapy for postoperative pulmonary 
hypertension. Journal of Thoracic and Cardiovascular Surgery. 2007;134(2):319-26. 

 
22 
9. 
Schwedhelm E, Maas R, Freese R, Jung D, Lukacs Z, Jambrecina A, et al. 
Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: 
impact on nitric oxide metabolism. British Journal of Clinical Pharmacology. 
2008;65(1):51-9. 
10. 
Richardosn DK, Corcoran JD, Escobar GJ, Lee SK, Canadian NN, Kaiser 
Permanente Neonatal Data S, et al. SNAP-II and SNAPPE-II: Simplified newborn illness 
severity and mortality risk scores. Journal of Pediatrics. 2001;138(1):92-100. 
11. 
Moinard C, Nicolis I, Neveux N, Darquy S, Bénazeth S, Cynober L. Dose-ranging 
effects of citrulline administration on plasma amino acids and hormonal patterns in 
healthy subjects: the Citrudose pharmacokinetic study. Br J Nutr. 2008;99(4):855-62.