Comparing different responses of the cough reflex

Not Applicable

Active, not recruiting

• Conditions: Cough challenge responses; Respiratory

• Registration Number: ISRCTN96855098
• Lead Sponsor: niversity of Manchester

Brief Summary

Not available

Detailed Description

Not available

Study Timeline

• Study Start: 2021-09-16
• Last Update Posted: 8 July 2024
• Study Completion: 2025-06-30

Recruitment & Eligibility

• Status: Ongoing
• Sex: All
• Target Recruitment: 24

Inclusion Criteria

Current inclusion criteria as of 21/06/2024:
1. Aged =18 years
2. Normal spirometry (FEV1 and FVC %predicted of =80%)
3. No current or past history of chronic cough or any other respiratory disease
4. No current or history of chronic pain, irritable bowel syndrome, psychiatric illness or chronic headaches
5. No previous experience of performing cough challenges (capsaicin study arm only)
6. Must cough at least 2 times on a single inhalation of any dose of capsaicin/citric acid during the visit 1 cough challenge

Previous inclusion criteria:
1. Aged =18 years
2. Normal spirometry (FEV1 and FVC %predicted of =80%)
3. No current or past history of chronic cough or any other respiratory disease
4. No current or history of chronic pain, irritable bowel syndrome, psychiatric illness or chronic headaches
5. No previous experience of performing cough challenges
6. Must cough at least 2 times on a single inhalation of any dose of capsaicin during the visit 1 cough challenge

Exclusion Criteria

Current exclusion criteria as of 21/06/2024:
1. Current smoker or ex-smoker with >20 pack-year history, and/or <6 months abstinence
2. Upper respiratory tract infection within the last 4 weeks
3. Use of ACE inhibitors
4. Use of anti-depressants
5. Use of centrally acting medications that may alter the cough reflex e.g. opiates
6. History of drug or alcohol abuse
7. Current pregnancy or breastfeeding
8. Concomitant conditions that may alter cough reflex sensitivity e.g. diabetes mellitus, Parkinson’s disease, cerebrovascular disease
9. Previous cough challenge experience (only applicable for capsaicin study arm)

Previous exclusion criteria:
1. Current smoker or ex-smoker with >20 pack-year history, and/or <6 months abstinence
2. Upper respiratory tract infection within the last 4 weeks
3. Use of ACE inhibitors
4. Use of anti-depressants
5. Use of centrally acting medications that may alter the cough reflex e.g. opiates
6. History of drug or alcohol abuse
7. Current pregnancy or breastfeeding
8. Concomitant conditions that may alter cough reflex sensitivity e.g. diabetes mellitus, Parkinson’s disease, cerebrovascular disease
9. Previous cough challenge experience

Study & Design

• Study Type: Interventional
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Maximum cough response (Emax) is measured at visit 1 and visit 2

Secondary Outcome Measures

Name	Time	Method
Current secondary outcome measures as of 21/06/2024:<br>1. Capsaicin and citric acid concentrations evoking at least 50% of the Emax cough number (ED50) is measured at visit 1 and visit 2<br>2. Concentration of capsaicin evoking at least two coughs (C2) is measured at visit 1 and visit 2<br>3. Capsaicin and citric acid concentrations provoking at least five coughs (C5) is measured at visit 1 and visit 2<br><br>Previous secondary outcome measures:<br>1. Capsaicin concentrations evoking at least 50% of the Emax cough number (ED50) is measured at visit 1 and visit 2<br>2. Concentration of capsaicin evoking at least two coughs (C2) is measured at visit 1 and visit 2<br>3. Capsaicin concentrations provoking at least five coughs (C5) is measured at visit 1 and visit 2