Pathophysiology and Pharmacology of Asthma

Question 1

What is asthma ?

Answer 1

• widespread narrowing of airways
• this narrowing changes spontaneously or as a result of treatment

Question 2

Factors influencing the development of Asthma

Answer 2

HOST FACTORS
- genetics
- obesity
- gender

ENVIRONMENTAL FACTORS
- allergens
- viral infection
- occupational irritants
- tobacco smoke
- air pollution
- diet

Question 3

Symptoms of Asthma

Answer 3

• wheezing
• breathlessness
• chest tightness
• coughing

Question 4

Causes of airway narrowing in asthma

Answer 4

• smooth muscle contraction
• inflammation
• airway oedema
• airway wall thickening
• mucus hypersecretion

Question 5

Cells involved in mediating pathophysiology of asthma

Answer 5

• Dendritic cells = present allergens to lymphocytes
• T lymphocytes and B lymphocytes = produce IgE antibodies against the allergen
• mast cell = IgE produced by lymphocytes is inserted onto the surface of mast cells. Allergen bind to these IgE’s and lead to the release of inflammatory mediators from mast cells
• Eosinophils = these white blood cells are attracted by IgE’s and mast cells. They release mediators that cause bronchospasm, mucus production and tissue damage

Question 6

Tissue remodelling in severe asthma

Answer 6

• epithelial shedding
• fibrosis
• increased mucus production
• increase in the mass of smooth muscle
• dilation of blood vessels, increased blood vessel permeability and plasma exudation leading to oedema

Question 7

Trigger factors for an increase in asthma symptoms

Answer 7

• viral infection
• bacterial infection
• irritants
• exercise
• weather changes
• GORD
• Pregnancy
• stressful and emotional situations

Question 8

Asthma Therapy

Answer 8

Relievers = for the immediate relief of symptoms

Controllers or preventers = prevent asthma attacks

Question 9

Relievers therapy

Answer 9

BRONCHODILATORS
- increase cAMP synthesis in smooth muscle
- short acting - salbutamol
- long acting - salmeterol

PHOSPHODIESTERASE INHIBITORS
- increase cAMP by inhibiting its breakdown.
- short acting oral theophylline

ANTI-CHOLINERGICS
- short acting inhaled = ipratropium bromide
- long acting - tiotropium bromide

Question 10

Controllers or preventers therapy

Answer 10

CORTICOSTEROIDS
- oral prednisolone
- inhaled budesonide
- combination of fluticasone plus salmeterol

LEUKOTIENE MODIFIERS
- leukotriene receptor antagonists
- inhibitors of leukotriene synthesis

PHOSPHODIESTERASE INHIBITORS
- sustained release theophylline
- roflumilast = far less side effects

ANTI-IgE
- omalizumab = used in treatment of severe asthma