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NCT Number: NCT03885245

Supplementing L-citrulline to Overweight Late Asthma oNset Phenotypes

Patients with obese late onset (after childhood) asthma can have lower FeNO levels, yet be highly symptomatic and poorly responsive to inhaled steroids. This is a common asthma phenotype, particularly among females. This reduction of NO occurs through increased arginase activity and uncoupling of NO synthase (NOS), by accumulation of asymmetric di-methyl arginine (ADMA), which further lowers the L-arginine/ADMA ratio, preferentially promoting reactive oxygen species (ROS) formation and inflammation at the expense of NO. Indeed, in patients with obese late onset asthma, lower L-arginine/ADMA plasma ratios are associated with reduced FeNO, increased bronchial hyperreactivity, and greater asthma morbidity. In our pilot studies, the administration of L-citrulline, as an L-arginine donor, to patients with obese late onset asthma increased the L-arginine/ADMA ratio, FeNO levels, and improved asthma control and lung function. Therefore, the objectives of the protocol are to: a) determine the efficacy of L-citrulline, as an add-on treatment to improve the asthma control and lung function in obese late onset asthmatics; b) leverage the use of asthmatic and control cells to further understand obesity-related changes in epithelial airway NO metabolism, and how these changes relate to bronchoconstriction and lung function, c) determine airway epithelial changes in mitochondrial function and bioenergetics in obese late onset asthmatics and how these are modified by L-citrulline. To do this, 54 obese late onset asthmatics with suboptimal control will be blindly randomized, in a cross over study, comparing 15g/day of L-citrulline vs. placebo, in two 8-week treatment periods with a 6-week washout in between. The co-primary study outcomes are asthma control (ACQ, ACT) and FeNO, and secondary endpoints plasma L-arginine/ADMA, FEV1 and PC20 methacholine. Parallel to this study, a small study of 10 healthy obese controls will receive open label L-citrulline for 7 weeks to establish comparative reference values for the study aims. During the initial treatment phase, 50% of study participants will be randomly allocated to undergo pre and post L-citrulline treatment bronchoscopy to obtain BAL and airway epithelial cells. The research group proposing this study is highly experience in asthma clinical trials, implementation of cross over design studies, and in the use of research bronchoscopies.

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Key information

Conditions

Asthma Body Weight Bronchial Diseases Hypersensitivity Hypersensitivity, Immediate Immune System Diseases Lung Diseases Lung Diseases, Obstructive Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Respiratory Hypersensitivity Respiratory Tract Diseases Signs and Symptoms

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adequate completion of informed consent process
  • Male and female patients
  • Physician diagnosis of asthma
  • Able to perform reproducible spirometry according to ATS criteria
  • Pre-bronchodilator FEV1 >/= 50% of predicted at Visit 0
  • Confirmation of asthma
  • All racial/ethnic backgrounds may participate.
  • BMI >/= 30
  • Regular treatment with ICS or ICS/LABA or LAMA combination medication for at least 1 month; participants can be on biologics.
  • Smoking history </= 10 pack years and no smoking in the last 3 months
  • Age of asthma onset (diagnosis) >/= 12 years
  • FeNO </= 30 ppb
  • ACQ >/= 0.50 or ACT </=19

Exclusion criteria

  • Respiratory tract infection within the 4 weeks prior to Visit 1
  • Oral or systemic corticosteroid burst (for any indication) within the 4 weeks prior to Visit 0. (One-time doses, such as intra-articular injections into a shoulder or knee joint, require a 4-week washout prior to Visit 0)
  • Asthma-related ER visit within the previous 4 weeks of Visit 0
  • History of ICU admission/intubation due to asthma in the past 1 year
  • 3 or more asthma exacerbations requiring treatment with systemic corticosteroids for more than three days in the past year consistent with severe asthma
  • Asthma exacerbation requiring systemic corticosteroids within the 4 weeks prior to Visit 0.
  • Chronic renal failure
  • Positive urine cotinine or THC test on the day of the bronchoscopy visit
  • Positive urine (or serum) pregnancy test at Visit 0 or at any time during the study
  • Intolerance or allergy to L-arginine or L-citrulline
  • Concomitant use of PDE5 drugs or oral mononitrates
  • Untreated sleep apnea
  • Participant in an interventional drug study or use of investigative drugs within the past 30 days or plans to enroll in such a trial during the study

Treatment and study plan

L-ctirulline

Drug

7 weeks of treatment with 15 g/day of orally administered (powder form mixed with water) L-citrulline

Other names: L-citrulline

Matching Placebo

Drug

7 weeks of treatment with orally administered matching placebo (to 15 g/day of L-citrulline)

Primary outcomes

  1. Change in Asthma Control Questionnaire

    Time frame: Through study completion, up to 32 weeks

    to determine L-citrulline efficacy, reduction in questionnaire scores determined by administering the questionnaires before, mid-way, and after during each treatment phase to see if there's a change in scores.

  2. Change in Asthma Control Test

    Time frame: Through study completion, up to 32 weeks

    To determine L-citrulline efficacy, reduction in questionnaires scores determined by administering the questionnaires before, mid-way, and after during each treatment phase to see if there's a change in scores.

Study contacts

Contact information is provided by the study sponsor or research team.

Asthma Research

CONTACT

[email protected]

1 (844) 365-0852

Sponsors and collaborators

Lead sponsor

University of Colorado, Denver

Other

Collaborators

  • Duke University
  • National Heart, Lung, and Blood Institute (NHLBI)
  • National Institutes of Health (NIH)

Registry information

Official study title

Supplementing L-citrulline to Overweight Late Asthma oNset Phenotypes to Increase Airway L-arginine/ADMA Ratio and Improve Asthma Control

Acronym: SANDIA

Important dates

Study start
2021
Primary completion
2025
Study completion
2026
First posted
Mar 21, 2019
Registry last updated
Jun 10, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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