Methacholine Challenge: Comparison of Doubling and Quadrupling Methacholine Dose Regimes Using the Tidal Volume Method

Study Overview
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Brief Summary
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The purpose of this study is to determine the difference (if any) in the result of the methacholine challenge (a test used by physicians in diagnosing asthma) when concentrations of methacholine are quadrupled versus doubled.

Detailed Description
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The purpose of this study is to confirm that the tidal volume technique of methacholine delivery may be employed in methacholine challenges using a quadrupling dose schedule instead of the standard doubling dose schedule with similar diagnostic efficacy, with no increase in patient adverse events, and with a shorter investigational duration. This has previously been shown to be true using the dosimeter technique of methacholine challenge.

Official Title
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Methacholine Challenge: Comparison of Doubling and Quadrupling Methacholine Dose Regimes Using the Tidal Volume Method

Conditions
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Asthma

Intervention / Treatment
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* Drug: Methacholine challenge


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: You must be over 18 years of age; and You must have a diagnosis of asthma; and Excluding asthma, you are not aware of any other lung conditions or diseases. Exclusion Criteria: You have a known hypersensitivity (i.e. an overreaction of your immune system) to methacholine or other parasympathomimetic agents or cholinesterase inhibitors (i.e. agents that act in a similar way via your nervous system - to be discussed with study personnel); or You are a nursing mother or if you are a woman of child bearing potential who is, may be, or intends to become pregnant during testing as the effects of methacholine inhalation in these situations are not known; or Your baseline lung function is poor (ie. your FEV or forced expiratory volume in one second, is less than 65% of your predicted values). This will be performed and explained by study personnel prior to commencing methacholine inhalation testing; or You have had any respiratory infections for the last four weeks; or If you have allergies, and have been exposed to agents that trigger your asthma within the last four weeks; or If you have any significant chronic medical condition.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Quadrupling<br>methacholine challenge using quadrupling concentrations | Drug: Methacholine challenge<br>* Clinical and research test used in asthma<br>|
| Active Comparator: doubling<br>doubling concentrations of methacholine | Drug: Methacholine challenge<br>* Clinical and research test used in asthma<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Methacholine PC20 |  | 1 week | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Subject measure of breathlessness - modified Borg scale |  | 1 week |