This clinical study is designed to explore dose ranging and identify methods to demonstrate the efficacy of Erdosteine in patients with stable Chronic Bronchitis associated with Chronic Obstructive Pulmonary Disease.

Inclusion Criteria:

• Adult patients with a clinical diagnosis of stable CB associated with COPD will be entered into this study. CB is diagnosed clinically in patients who have a documented smoking history and who have a daily productive cough for at least 3 months per year over at least 2 consecutive years in the absence of other causes of chronic cough. COPD is defined by the presence of airflow obstruction from spirometry

Exclusion Criteria:

asthma, bronchiectasis, or cystic fibrosis; active history of lung cancer, respiratory failure, or a need for long-term oxygen therapy;