Novel Endpoints in Cough Challenge Testing

Inclusion criteria

• Adult subjects aged 18 and over.

Meet criteria for subject groups as outlined below:

Healthy volunteers:

• Must be non smokers.
• No history of respiratory disease.

Healthy smokers:

• Current smokers with at least 10 pack year history of smoking.
• Spirometry within normal limits i.e. FEV1 > 80% predicted and FEV1/FVC ratio of > 75% predicted.

Asthma:

• Physician diagnosis of asthma
• Stable asthma.
• Airway hyperresponsiveness to methacoline; PC20< 16mg/ml.
• Non smokers or ex-smokers with smoking history of less than 10 pack years.

COPD:

• Physician diagnosis of COPD
• Ex smokers with smoking history of at least 20 pack years
• Spirometry demonstating evidence of airflow obstruction i.e. FEV1/FVC ratio of < 70%

Chronic cough:

• History of dry cough for at least 8 weeks.
• Normal chest x ray.
• Non smokers or ex smokers of less than 10 pack years history of smoking.

Exclusion criteria

• Symptoms of upper respiratory tract infection within the last 4 weeks.
• Participation in another clinical trial of an investigational drug within 4 weeks.
• Use of medication likely to alter cough reflex sensitivity i.e. ACE inhibitors, codeine phosphate, morphine sulphate.
• Patients with severe respiratory disease i.e. FEV1 < 1.0 litre.
• Use of steroid tablets in previous 2 months or taken more than 3 courses of steroid tablets in the preceding 12 months in subjects with asthma or COPD.
• Change in asthma treatment in the preceding 6 weeks in asthma group
• Significant medical co-morbidities likely to affect ability to participate in the trial or affect cough reflex sensitivity e.g. diabetes, stroke, Parkinson's disease, multiple sclerosis etc.