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Cough | An Investigation Into the Mechanism of Inhalation Cough Challenge

Cough research study

What is the primary objective of this study?

Despite its commonplace use in respiratory medicine the mechanism whereby inhalation challenge with a variety of mild acid aerosols produces a dose related and predictable cough is unknown. In this proposal the investigators wish to use established cough challenge methodology to explore the mechanism of action of agents provoking cough both in health and disease. The hypotheses to be tested include: - Intracellular changes in pH, rather than extracellular changes, are key in the activation of TRP receptors, the main sensor for provoking cough. - ATP acting through P2X channels is the mechanism of increased nerve excitability underlying cough hypersensitivity.

Who is eligible to participate?

Inclusion Criteria: - Patients will be required to demonstrate significant cough symptoms by a score greater than 20/70 on the Hull Airways Reflux Questionnaire. - All patients must be current non-smokers. - Patients must be on stable medication for at least one month. - Patients must be able to attend the trials unit on at least 3 occasions. - Patients must have normal lung function patients must be able to give informed consent Exclusion Criteria: - Subjects who are pregnant, or have pacemakers in situ are excluded from this study. - Those with a serious comorbid conditions such as cancer, severe COPD, or heart failure will be excluded. - Those who are non-English speakers and special groups (i.e. mentally ill, children under 16 years of age, and those suffering from dementia) will be excluded. - No test will be performed on any subject during an acute worsening of asthma or upper airway infection. If the subject has had an upper airway infection in the last three weeks they will be offered another appointment. - If the subject has taken any over the counter (OTC) cough mixture within the last twelve hours: If the subject is willing to come back another time for challenge testing, another appointment should be made. - If the subject has had any food or drink products containing caffeine or menthol within the last hour. If the subject is unwilling to wait for 1 hour before starting the test, the subject should return another time. If the subject is unwilling to return another time, testing should proceed and the medication used recorded. - If the participant is currently involved in research, or within 3 months of participation in any type of research, they will be excluded from this study.

Which medical condition, disease, disorder, syndrome, illness, or injury is researched?

Cough

Study Interventions

Interventions can include giving participants drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available or noninvasive approaches such as surveys, education, and interviews.

Other:Nebulised citric acid in serial dilutionsCitric acid will be delivered in serial dilutions as per the clinical trials unit standard operating procedure for cough challenge using KoKo Digidoser, based on ERS guidelines. Challenge will be repeated until C5 (5 coughs in 30 seconds following challenge) is elicited.

Other:Nebulised ATP solution in serial dilutionsATP solution will be delivered in serial dilutions as per the clinical trials unit standard operating procedure for cough challenge using KoKo Digidoser, based on ERS guidelines. Challenge will be repeated until C5 (5 coughs in 30 seconds following challenge) is elicited.

Other:Nebulised TRPA1 agonist solution in serial dilutionsTRPA1 agonist will be delivered in serial dilutions as per the clinical trials unit standard operating procedure for cough challenge using KoKo Digidoser, based on ERS guidelines. Challenge will be repeated until C5 (5 coughs in 30 seconds following challenge) is elicited.

Study Arms

Research studies and clinical trials typically have two or more research arms. An arm is a group of people who receive the same treatment in the study.

Chronic coughCough challenges to be administered include: Nebulised citric acid in serial dilutions Nebulised ATP solution in serial dilutions Nebulised TRPA1 agonist solution in serial dilutions

Normal volunteerCough challenges to be administered include: Nebulised citric acid in serial dilutions Nebulised ATP solution in serial dilutions Nebulised TRPA1 agonist solution in serial dilutions

Study Status

Completed

Start Date: February 2015

Completed Date: August 2016

Phase: N/A

Type: Interventional

Design:

Primary Outcome: Difference in mean C5 (concentration of inhaled substance required to elicit 5 coughs) (ATP) and total cough (citric acid) between the chronic cough arm and the normal volunteer arm.

Secondary Outcome:

Study sponsors, principal investigator, and references

Principal Investigator: Alyn H Morice, MD, FRCP

Lead Sponsor: Hull and East Yorkshire Hospitals NHS Trust

Collaborator:

More information:https://clinicaltrials.gov/show/NCT02039999

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