Asthma and its prevention

Asthma

Asthma – Basic introduction and causes:

Bronchial Asthma – Hyper-responsiveness of trachio-bronchio smooth muscle to variety of stimuli.

This result into narrowing of airtube , increase the secretion, mucosal edema, mucus plugging

Symptoms:  Dyspnoea, Wheezing sound, Cough and limitation of activity.

Triggering factors: Infection, Irritation, Pollution, Cold air, Smoking etc.

Types:

1) Extrinsic: a) Start in an early age

                     b) Episodic (an internal)

                     c) Patient has history of allergies (family).

2) Intrinsic: a) Start in middle age

                    b) Assumes as chronic form.

                    c) There is no family history of allergies.

Initiation of Asthma:

Inflammation starts with Mast cell (present in lungs).

Then Inflammation produce following mediators:

·         Release of intracellular granules: Histamine, Protease enzyme.

·         Release of phospholipids from cell membrane: PGs and LTs.

·         Activation of Gene followed by protein synthesis: IL, TNF-α.   

Asthma: Steps in inflammatory Reaction:

Ø  Allergens inhaled:         Asthma attack begins causes   decreases in Breathing.

Ø  Allergens bind to Ig E that have binding site for allergens.

Ø  Allergen + Ig E = Trigger the release of – Histamine and LTs.

Ø  Leukotriens- Bronchial smooth muscle contraction, therefore the lumen size decreases, hence while respiration problem occurs.

    At Early phase:           Activation of T-helper-2 cells then 

                                      increases in Production of IL₁ 

                                      _{increases in  level of Ig E}

                Allergens-      Binding of Ig E in Mast cell

                                      Release of Histamines

                                     Broncho Constriction- Bronchioles Spasm

                                       increases airway hyperacidity                       

Approaches to Treatment:

1) Prevention of AG:AB reaction:- Avoidance of antigen hypersensitization- possible in            Extrinsic Asthma

2) Neutralisation of IgE (Reaginic Antibody): Omalizumab can be given

3) Suppression of Inflammation and Bronchial hyper-reactivity: Mast cell stabilization

4) Antagonism of released mediators: Leukotriene antagonist, Antihistaminic drugs

5) Blockade of constriction Neurotransmitter: Anticholinergic drugs

6) Mimicking Dialator Neurotransmitter: Sympathomimetic

7) Direct Acting Bronchodilators: Methylxanthine                               

Classification:

—  1) A. Bronchodilators
1. β2 Sympathomimetics: Salbutamol, Terbutaline,Bambuterol, Salmeterol, Formoterol, Ephedrine.
2. Methylxanthines: Theophylline, Aminophylline
3. Anticholinergics: Ipratropium bromide, Tiotropium bromide.

—  B. Leukotriene antagonists
Montelukast, Zafirlukast.

—  C. Mast cell stabilizers
Sodium cromoglycate, Ketotifen.

—  D. Corticosteroids
1. Systemic: Hydrocortisone, Prednisolone and others.
2. Inhalational: Beclomethasone dipropionate,
Budesonide, Fluticasone propionate, Flunisolide,
Ciclesonide.

—  E. Anti-IgE antibody
Omalizumab.

 Thank you