Mr Lee, a 58 year old smoker with severe chronic obstructive pulmonary disease (COPD) (FEV1 43% predicted), is admitted with an acute exacerbation of COPD for the second time in the past month. He presented to the Accident and Emergency Department with increased productive cough and shortness of breath, similar to prior exacerbations. Physical examination is notable for bilateral inspiratory and expiratory wheezing. His sputum is purulent. He is given continuous nebulizer therapy of bronchodilator and one dose of oral prednisone, but his dyspnea and wheezing persist. Chest X-ray reveals an infiltrate.

Expanding further on the terms used in the question and the topic of COPD:

FEV1 is a pulmonary function test (spirometry) and means Forced Expiratory Volume – the amount of air a person can forcefully exhale in one second. 

Predicted FEV1 values for an individual increases over time up until the age of 20-30, then gradually declines with age.

These values can be used as a measure to stage a patient's degree of COPD. A person with 43% FEV1 compared to the predicted value of someone who doesn’t have COPD is classed as having severe COPD according to GOLD staging.

Purulent sputum means sputum containing pus.

Dyspnoea means shortness of breath or difficulty breathing which is the hallmark symptom of COPD

Pulmonary infiltrate means a substance other than air is seen in the lungs, ie pus or blood and is often associated with pneumonia

COPD exacerbations contribute to disease progression, which is even more likely if recovery from exacerbations is slow. And once a COPD patient experiences an exacerbation, they will show increased susceptibility to another event.

Patients who are particularly susceptible to frequent exacerbations (>2 two per year), have worse health status and morbidity than patients with less frequent exacerbations.

Why an individual may have increased susceptibility to exacerbations remains largely unknown.

The three classes of medications most commonly used for COPD exacerbations are bronchodilators, corticosteroids, and antibiotics.

In hospital oxygen is important in the treatment of exacerbations. In severe cases mechanical ventilation may be required.  

a) Name TWO major classes of drugs with one example each that are commonly used as bronchodilators in the treatment of COPD. Describe their mechanisms of action (8 marks)

Four points for each class.

1 point for naming class

1 point for example

2 points for MOA.

Two major classes: Beta-2 adrenoceptor agonists and anti-muscarinics

Beta-2 adrenoceptor agonists 

MOA: Activation of the beta-2 adrenergic receptors in the airways.

Beta adrenoceptors are activated by the sympathetic nervous system in the fight or flight response which causes bronchodilation to increase lung function.

Note the question only asks for one example but I will include all:

Beta-2 receptor agonists vary in their duration of action:

• Short acting (SABA): salbutamol and terbutaline
• Long acting B2 receptor agonists (LABAs): include salmeterol, formoterol, and the ultra-long acting B2 receptor agonists.
• Ultra-long acting B2 receptor agonist: Indacetarol, vilanterol, oladeterol. These have a long half life and can be administered by inhalation once a day.

Anti-muscarinic eg. ipratropium (Atrovent)

MOA: The sympathetic nervous system is opposed by the parasympathetic nervous system. Stimulation by acetylcholine on the muscarinic receptors causes bronchoconstriction. Anti-muscarinic agents blocks parasympathetic activity inducing bronchodilation.

Short acting anti-muscarinic (SAMA): ipratropium

Long acting anti-muscarinic (LAMA): tiotropium, aclidinium, glycopyrronium, umeclidinium

Bronchodilator medications in COPD are most often given on a regular basis to prevent or reduce symptoms.

In exacerbations SABAs are used, but for regular maintenance long acting LABAs and LAMAs are used.

Ref

BNF

GOLD