Mr Lee, a 75 year old man, made a regular visit to his general practitioner and complained of gradual deterioration in exercise and tolerance, as he could only manage to climb up one flight of stairs once year ago. He has been a chronic smoker for the past 50 years, with an average daily consumption of one pack of cigarettes. He has been having chronic cough with whitish sputum production almost daily in the past five years.

a) What is his most likely condition? (2 marks)

b) Name TWO major classes of drugs with one example each that are commonly used as bronchodilators in the pharmacological treatment of this condition. Describe their mechanisms of action and routes of administration. (10 marks)

c) Which combination therapy is currently approved for better daily treatment of this condition instead of monotherapy? What is the rationale for such drug combination? (4 marks)

d) Which class of therapeutic drug with one example can be added to relieve his chronic cough with whitish sputum production? State the mechanism of action. (4 marks)