Asthma

Definition:-
“Asthma is a disease characterized by airway inflammation & episodic reversible bronchospasm.”

What Is The Pathophysiology of Asthma?
Bronchoconstriction is associated with asthma & the immediate cause of it is the release of several mediators from IgE-sensitized mast cells & other cells involved in immunologic responses.

The antigen is presented to peripheral lymphoid tissue which causes synthesis of IgE. IgE in turn binds to mast cells & sensitizes it & other inflammatory cells as well. The challenging of these sensitized cells with antigen results into massive release of a variety of mediators which account for signs of bronchoconstrictor response in asthmatics.
The mediators released are;

• Leukotrienes LTC₄, LTD₄, LTB₄ (Chemotactic mediator which attracts inflammatory cells to the airway)
• Cytokines
• PGD₂ (prostaglandins 2)
• ECF-A
• Some enzymes like tryptase

These mediators lead to chronic inflammation which results into hyper-reactivity (mediated by Vagal Reflexes) to various inhaled substances like;

• Cold air
• Antigens
• Histamine
• Irritants like SO2
• Muscarinic agonists

What Are Therapeutic Strategies In Asthma?
Therapeutic strategies are done in two categories (bases upon onset of bronchospasm i-e acute or chronic);

1. Pharmacological therapies
2. Non-pharmacological therapies

What Are Non-Pharmacological Therapies In Asthma?
Non-pharmacological therapies include mainly…..

What Are Pharmacological Therapies In Asthma?
Pharmacological therapies include;

Bronchodilators / Reliever Drugs (Smooth Muscles Relaxants)

• Sympathomimetics (β-selective agonists)
• Muscarinic antagonists
• Methyxanthines
• Leukotriene receptors blockers (Leukotriene receptors blockers have effects on both bronchoconstriction & inflammation but are used for prophylaxis only)

φ Acute bronchospasm must be treated promptly & effectively with bronchodilators!

Anti-inflammatory Agents

• Corticosteroids (Long acting β-selective agonists improve response to corticosteroids so used with corticosteroids)
• Mast cell stabilizers
• Anti-IgE antibody

φ Chronic asthma is treated with anti-inflammatory agents, the most important of which are corticosteroids!

What Are Bronchodilators / Reliever Drugs?

Sympathomimetics (β-selective agonists)

continue…

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