2.08 - Drugs Used In Managing Respiratory Conditions

Question 1

Describe Asthma

Answer 1

A chronic inflammatory disorder of the airways in which many cells and cellular elements play a role, in particular, mast cells, eosinophils, T lymphocytes, macrophages, neutrophils, and epithelial cells.
In susceptible individuals, this inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning.
These episodes are usually associated with widespread but variable airflow obstruction that is often reversible either spontaneously or with treatment.
The inflammation also causes an associated increase in the existing bronchial hyper-responsiveness to a variety of stimuli.

Question 2

What are the causes of the airway narrowing in Asthma?

Answer 2

Smooth muscle hypertrophy and hyperplasia
Inflammatory cell infiltration
Oedema
Goblet cell and mucous glad hyperplasia
Mucus hypersecretion
Protein deposition including collagen
Epithelial desquamation

Question 3

Describe COPD

Answer 3

COPD is characterised by airway inflammation and airflow limitation that is not fully reversible.
It is a progressive, disabling disease with serious complications and exacerbations that are major burdens for healthcare systems

Question 4

Describe the use of short acting beta2 agonists

Answer 4

Salbutamol
Onset: rapid, maximum within 30mins, Duration: 3-5hours
Stimulation of beta2 receptors on airway smooth muscle relaxes the muscle resulting in bronchodilation
Preffered route of administration is inhalation
Can also stimulate beta1 receptors leading to tachycarida, tachyarrhythmias, tremor

Question 5

Describe the use of long acting beta2 agonists

Answer 5

Salmeterol
Onset: 30-40mins, Duration: 8-12hours
Usually given in combination with inhaled corticosteroids
Similar adverse events as short acting beta2 agonists

Question 6

Describe the use of anticholinergic bronchodilators

Answer 6

Ipratropium (short-acting) but more recently tiotropium (long-acting)
Block the muscarinic receptors in the lung preventing parasympathetic mediated bronchoconstriction and mucous production
Inhaled powders
Adverse side effects, parasympathetic activation –> dry mouth, constipation, depression, angina, urinary retention, glaucoma

Question 7

Describe the use of Xanthine bronchodilators

Answer 7

Theophylline
Oral administration
Relax smooth muscle, mechanism not well understood

Question 8

Describe the use of chromoglycates

Answer 8

Sodium chromoglycate
Inhalation
Do not relieve acute symptoms –> used in prophylactic treatment.
Thought to prevent mast cell degranulation
Not used much anymore

Question 9

Describe the used of leukotriene antagonists

Answer 9

Montelukast
Selective antagonist of leukotrienes LTC4, LTD4 and LTE4
Results in relaxation of smooth muscle and some reduction of inflammation mediated by leukotrienes
Tablet form
Large therapeutic window

Question 10

Describe the use of Inhaled corticosteroids

Answer 10

Beclamethasone
Preventative therapy in asthma, not used acutely
Generally no system effects, unless dose is large
Bind to glucocorticoid receptors and inhibit the activation of pro-inflammatory genes. Can also, in high concentrations, activate anti-inflammatory genes