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Diesel Exhaust and Mechanism of Asthma

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT01699204
First Posted: October 3, 2012
Last Update Posted: September 29, 2017
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by (Responsible Party):
Christopher Carlsten, University of British Columbia
  Purpose
This experiment is designed to test the hypothesis that oxidative stress is responsible for changes in airway responsiveness in humans exposed to diesel exhaust.

Condition Intervention
Asthma Dietary Supplement: N-acetylcysteine Other: Diesel exhaust Other: Filtered air

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: Effects of Diesel Exhaust on Airways

Resource links provided by NLM:


Further study details as provided by Christopher Carlsten, University of British Columbia:

Primary Outcome Measures:
  • Human airway reactivity [ Time Frame: 50 hours ]
    Establish that oxidative stress is responsible for changes in human airway reactivity induced by DE (300 µg/m3 inhaled for two hours).


Enrollment: 26
Study Start Date: September 2007
Study Completion Date: October 2011
Primary Completion Date: October 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Placebo Comparator: Filtered air with placebo
Exposure for 2 hours to filtered air and placebo tablets 3 times daily for 6 days
Other: Filtered air
A placebo tablet taken 3 times daily for 6 days prior to exposure to filtered air for 2 hours. The last supplement was taken the morning of the exposure
Active Comparator: Diesel exhaust with placebo
Exposure for 2 hours to diesel exhaust and placebo tablets 3 times daily for 6 days
Other: Diesel exhaust
A placebo tablet taken 3 times daily for 6 days prior to exposure to diesel exhaust for 2 hours. The last supplement was taken the morning of the exposure
Experimental: Diesel exhaust with N-acetylcysteine
Exposure for 2 hours to diesel exhaust and N-acetylcysteine tablets (600 mg) 3 times daily for 6 days
Dietary Supplement: N-acetylcysteine
N-acetylcysteine 600mg taken orally 3 times daily for 6 days prior to exposure to diesel exhaust for 2 hours. The last supplement was taken the morning of the exposure
Other: Diesel exhaust
A placebo tablet taken 3 times daily for 6 days prior to exposure to diesel exhaust for 2 hours. The last supplement was taken the morning of the exposure

Detailed Description:

The specific aim is to test the hypothesis that diesel exhaust (DE) increases airway reactivity via oxidative stress, particularly in asthmatics. To test this hypothesis, we use a crossover in vivo experimental model in mild asthmatics and normal controls using a state-of-the-art diesel exhaust exposure facility.

Participants took N-acetylcysteine (600 mg) or placebo capsules three times daily for six days. On the final morning of supplementation, participants were exposed for 2 hours to either filtered air or diesel exhaust (300 µg·m-3 of particulate matter smaller than 2.5 microns). Twenty-six non-smokers between 19-49 years were studied under three experimental conditions (filtered air with placebo, diesel exhaust with placebo and diesel exhaust with N-acetylcysteine) using randomized, double-blind, crossover design, with a two week minimum washout between conditions. Methacholine challenge was performed pre-exposure (to determine baseline airway responsiveness) and post-exposure (to determine the effect of exposure).

  Eligibility

Information from the National Library of Medicine

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Ages Eligible for Study:   19 Years to 49 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Between 19-49 years, non smokers, asthmatics, healthy controls

Exclusion Criteria:

  • Smokers, pregnant or co-existing medical condition for which diesel exhaust would confer significant risk (i.e. coronary artery disease)
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01699204


Locations
Canada, British Columbia
University of British Columbia
Vancouver, British Columbia, Canada, V5Z1M9
Sponsors and Collaborators
University of British Columbia
Investigators
Principal Investigator: Christopher Carlsten, MD MPH University of British Columbia
  More Information

Publications:

Responsible Party: Christopher Carlsten, Principal Investigator, University of British Columbia
ClinicalTrials.gov Identifier: NCT01699204     History of Changes
Other Study ID Numbers: H08-02288
First Submitted: October 1, 2012
First Posted: October 3, 2012
Last Update Posted: September 29, 2017
Last Verified: September 2017

Keywords provided by Christopher Carlsten, University of British Columbia:
Air pollution
Diesel exhaust
Airway responsiveness
Asthma
Anti-oxidant

Additional relevant MeSH terms:
Asthma
Bronchial Diseases
Respiratory Tract Diseases
Lung Diseases, Obstructive
Lung Diseases
Respiratory Hypersensitivity
Hypersensitivity, Immediate
Hypersensitivity
Immune System Diseases
Acetylcysteine
N-monoacetylcystine
Antiviral Agents
Anti-Infective Agents
Expectorants
Respiratory System Agents
Free Radical Scavengers
Antioxidants
Molecular Mechanisms of Pharmacological Action
Protective Agents
Physiological Effects of Drugs
Antidotes