Mr Lee, a 68-year-old taxi driver, had chronic obstructive pulmonary disease ("COPD”) with a chronic cough producing thick sputum, breathlessness and exercise limitation. The cough and sputum production have not changed recently. He stopped smoking for 3 months previously because of his dyspnea. Prior to his smoking cessation, he has been smoking 20 cigarettes a day for 50 years. He had no other significant medical illnesses. His forced expiratory volume in one second ("FEV1") was 1.34 L (about 45% of predicted). He was given the combination of ipratropium and salbutamol via a pressurized metered dose inhaler ("pMDI") for symptomatic relief. A trial of inhaled budesonide given 3 months previously provided no benefit and it has been stopped now. 

(a) Which classes of drugs do ipratropium and salbutamol belong to? (2 marks) 

(b) Describe the mechanisms of action for ipratropium and salbutamol. (6 marks) 

(c) Which class of drugs does budesonide belong to? State how this class of drugs works. (4 marks) 

(d) What will be the most appropriate combination inhaler with an example to replace the current medication for symptomatic relief? What is the rationale? (4 marks) 

(e) List ONE class of therapeutic drug with an example that can be used for add-on treatment to break down his thick sputum. State the mechanism of action for such a drug. (4 marks)