Inclusion Criteria:

• Diagnosis of COPD (history, spirometry, symptoms including chronic cough and/or shortness of breath that is worse on exertion and/or excess sputum production)
• Aged 45 - 80 years
• Have pre-bronchodilator FEV1 > 1.4 litres and at least 60% of predicted for height, age and gender and a post-bronchodilator FEV1 <80% of predicted for height, age and gender
• Post-bronchodilator FEV1/FVC < 70 %
• ≥ 10 pack years smoking history

• As determined by the investigator, are capable and willing to:

  • perform all of the techniques necessary to measure lung function;
  • administer the dry powder mannitol.
• Are capable of, and have given informed consent to, participating in this study in accordance with local regulations.

• The subject must be in stable clinical condition at the time of, and for a period of 14 days prior to, their recruitment into the study. Stable clinical condition is defined as lack of:

  • change in sputum production (volume, colour, consistency);
  • increased cough;
  • worsening dyspnoea;
  • increased malaise, fatigue or lethargy;
  • reduction in exercise tolerance;
  • fever;
  • antibiotic treatment (for respiratory infection).

Exclusion Criteria:

• Investigators, site personnel directly affiliated with this study, and their immediate families. Immediate family is defined as a spouse, parent, child or sibling, whether biologically or legally adopted.
• Subjects receiving treatment with inhaled corticosteroids (including combination therapies, e.g. Seretide®, Symbicort®) or oral corticosteroids within the last 6 weeks.
• Subjects who have had an exacerbation or a chest infection within the 2 weeks prior to the study.
• Subjects receiving antibiotic treatment for respiratory infection.
• Known diagnosis of asthma or allergic rhinitis.
• Myocardial infarction in the six months prior to enrolment.
• Cerebral vascular accident in the six months prior to enrolment.
• Ocular surgery in the three months prior to enrolment.
• Abdominal surgery in the three months prior to enrolment.
• Active tuberculosis (TB).
• Lung cancer or any other malignancies, which are considered by the investigator as a contraindication to participating in the study.
• Lung disease other than COPD (e.g. bronchiectasis).
• Uncontrolled insulin-dependant or non-insulin dependant diabetes, i.e. >10% HbA1c.
• Female subjects of reproductive capability, not using a reliable form of contraception
• Inability to obtain informed consent from the subject or subject's authorised representative.
• Subjects who have participated in another investigative drug study parallel to, or within 4 weeks of, study entry.
• Known intolerance to mannitol.
• Uncontrolled hypertension - systolic blood pressure (BP) > 200 mmHg and or diastolic BP > 100 mmHg.
• Planned pulmonary rehabilitation.
• Have had major abdominal, chest or brain surgery in the three months prior to enrolment.
• Have known cerebral, aortic or abdominal aneurysm.