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NCT Number: NCT00280683

Effects of L-arginine Supplementation in Adults With Moderate to Severe Asthma

Nitric oxide is an important marker of airway inflammation in asthma. Nitric oxide may have a protective role in patients with moderate to severe asthma. The investigators believe that a natural amino acid, L-arginine, that augments nitric oxide levels can decrease asthma exacerbations and improve the asthma care of moderate to severe asthma patients.

This study is a randomized, placebo controlled trial in which subjects will receive either 3 months of L-arginine supplementation or a placebo. The investigators will monitor subjects' symptoms, the number of asthma exacerbations, and lung function. In addition, we will draw blood, obtain induced sputum samples and measure exhaled breath nitric oxide levels at each monthly visit.

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Key information

Conditions

Asthma Bronchial Diseases Hypersensitivity Hypersensitivity, Immediate Immune System Diseases Lung Diseases Lung Diseases, Obstructive Respiratory Hypersensitivity Respiratory Tract Diseases

Age range

18 year–90 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

University of California, Davis General Clinical Research Center

Sacramento, California, 95817, United States

About this study

The primary objective of this 3 month clinical study is to determine if supplemental L-arginine can decrease the number of asthma exacerbations in patients with severe asthma. L-arginine, a natural amino acid, produces nitric oxide (NO) when it is converted to L-citrulline in the presence of the nitric oxide synthase enzymes. We and others have found that NO can protect against allergic airway inflammation, airway hyperresponsiveness and airway fibrosis in various animal models. In addition, we have found that arginase I expression correlates strongly with the lymphocyte and eosinophil influx into the lung and this enzyme may regulate the airway inflammatory response. Our central hypothesis is that L-arginine will increase NO levels in the lung and decrease the number of acute exacerbations of asthma. It may do this by either decreasing the number of Th2 lymphocytes or down-regulating arginase I expression or both.

Our specific aims are, therefore,

  • To test the hypothesis, in a randomized, double-blinded, placebo controlled trial, that 3 months of L-arginine supplementation will decrease the number of acute asthma exacerbations in severe asthmatic patients,
  • To determine whether L-arginine decreases the ratio of peripheral blood Th2 to Th1 lymphocytes and
  • To determine whether L-arginine will modulate serum arginase I/II levels and their downstream products.

Patients will be recruited primarily from the UC Davis Asthma Network (UCAN) clinics, which focus on the care of severe asthmatics, and the study will be performed at the UC Davis/VA General Clinical Research Center.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Moderate to severe persistent asthma
  • Subject is stable on same asthma medications for at least one month
  • If the subject is a woman of child-bearing age, a negative pregnancy test

Exclusion criteria

  • Less than 18 yrs/ age
  • Baseline Forced Expiratory Volume in 1 second (FEV1) <40% predicted
  • Known or suspected allergy to L-arginine
  • Pregnant women, nursing women, or women actively trying to achieve pregnancy
  • Current smokers
  • Subjects with more than a 15 pack-year history of smoking

Treatment and study plan

L-arginine

Drug

subjects will take matching 0.01 g/kg/day of L-arginine in divided doses for thre months.

Other names: Arginine 1000

Placebo

Drug

Placebo tablets that match the L-arginine intervention tablets will be given for three months

Other names: Matching placebo tablets

Primary outcomes

  1. Number of Asthma Exacerbations in Three Months

    Time frame: 3 months

    Asthma exacerbation is a composite endpoint. An asthma exacerbation is defined as any of the following: a) a drop in the morning peak expiratory flow rate (PEF) >30% from baseline on 2 consecutive days, b) a need for initiation of or increased dose of inhaled corticosteroids, or the c) doubling of short-acting rescue β-agonist drug use (e.g.Albuterol) on two consecutive days. Any one of these three counts as one asthma exacerbation.

Secondary outcomes

  1. L-arginine Serum Concentration

    Time frame: 90 days

Sponsors and collaborators

Lead sponsor

University of California, Davis

Other

Collaborators

  • National Center for Research Resources (NCRR)
  • National Institutes of Health (NIH)

Registry information

Official study title

Phase 2 Study: GCRC: Effects of L-arginine Supplementation on Exhaled Nitric Oxide and Clinical Exacerbations in Adults With Moderate to Severe Asthma

Important dates

Study start
2004
Primary completion
2008
Study completion
2008
First posted
Jan 23, 2006
Registry last updated
May 30, 2017

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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