Anti Asthmatics

8/6/2019 Anti Asthmatics

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Anti-Asthmatic Agents


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Contents:Definitions

MechanismPathology

Classification

Agents in detail


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ASTHMA:

It is physiologically characterized by

increased responsiveness of trachea and

bronchi to various stimuli and by wide spread

narrowing of the airways.


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FACTORS INFLUENCING ASTHMA


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The mechanisms underlying bronchial hyperactivity are

somehow related to inflammation of airway mucosa.

The agents that increase bronchial reactivity, such as

ozone exposure, allergen inhalation, and infection with

respiratory viruses, also cause airway inflammation.

MECHANISM


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PATHOLOGY

Its pathologic characters are contraction of airway

smooth muscle, mucosal thickening from edema and

cellular infiltration, and inspissations in the airwaylumen of abnormally thick, viscoid plugs of mucus.

The products of cells in the airways, such as eosinophil,

lymphocytes, macrophages, mast cells, sensory nerves,and epithelial cells, have been shown to alter airway

smooth muscle function.


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Asthma relievers-classification:

2 categories

Short term relievers:

b-adrenoceptorstimulants

Theophylline

Anti-muscuranic agents

Long term relievers:

Anti-inflamatory agents

Inhibitors of mast cell

degranulation


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b- adrenoceptor agonists are of

Non-selective agents

Adrenaline/epinephrine

Ephedrine

Isoproterenol

Selective agents

Salbutamol

Terbutaline

clenbuterol


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.Adrenoceptor agonists:

//mechanism

1. Stimulation of 2 receptor in bronchial

smooth muscle cell membrane cAMP Ca2+smooth musle relaxation .

2. Also activate receptor on mast cell mb. ,

thus used in prophylaxis of allergicasthma .


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3. Stimulation of receptor in bronchial vessels

contraction of vascular smooth muscle edema .

4. The density of receptor will decrease after

prolonged treatment.


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Adrenaline

/epinephrineAdrenaline

/epinephrine :

//agonist of and receptor

//adverse effect of cardiovascular system

usually occurs thereby less usable

//s.c.

Injection

EphedrineEphedrine

//orally administered

//similar action to Adrenaline//less usable for central excitation


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Isoproterenol//agonist of 1&2 receptor

//no action on receptor

//used for acute attack of bronchoasthma

by inspiration route//orally ineffective

//involved in adverse effect of 1 receptor

excitation.


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Selectively 2

receptor agonist

Salbutamol

Terbutaline

ClenbuterolClenbuterol

The 2-Selective adrenoceptor agonist drugs are the

most widely used sympathomimetics for the treatment

of asthma at the present time.


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//Mechanism :Air way smooth muscle has little

sympathetic nervous supply but contain lots of 2-

adrenoceptors that respond to circulating adrenaline.

The stimulation of 2-receptors leads to a rise

in intracellular cAMP levels and the subsequent

bronchial smooth muscle relaxation


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They are effective after inhaled or oral

administration and have a long duration of action

and significant 2 selectivity.

Given by inhalation , these agents cause

bronchodilation equivalent to that produced by

isoproterenol.


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22--adrenoceptoradrenoceptor agonistagonist maymay alsoalso helphelp toto preventprevent thetheactivationactivation ofof mastmast cellcell inin aa minorminor degreedegree ..

ModernModern selectiveselective 22--receptorreceptor agonistsagonists areare potentpotentbronchodilatorsbronchodilators andand havehave veryvery fewfew 11 --stimulatingstimulating

propertiesproperties..


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//Route of administrationRoute of administration :

usually delivered via a metered doseinhaler with immediate effect

orally used in children

iv used for acute-care.

S.C. (terbutaline)

//Adverse effectAdverse effect :

cardiac arrhythmias

tolerance to agonisthypoxemia


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They are divided into two types :

1. Salt complex :

Increased water solubility without augmentation of

pharmacological action , such as :

Aminophylline

Choline theophylline


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2. Agent of delayed release :

Small fluctuation of blood concentration after

oral administration thus used for nocturnal attact of

asthma protheo


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//Mechanism :

Anti-inflammation

inhibit activity of PDE cAMP Ca 2+

bronchial relaxation

increase the release of Noradrenaline,adrenaline

inhibition the cell surface receptor of adenosine

interfere with the transportation of Ca 2+


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//pharmacodynamics The bronchodilation is the major therapeutic action in

asthma.

Potent effects in improving contractility and in

reversing fatigue of diaphragm in patients with chronicobstructive lung diseases.

Direct positive chronotropic and inotropic effects on

the heart.

In large doses, these agents also relax vascular smooth

muscle.


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//Administration route : orally effectivebut different from adrenergic agent for

metabolism by P450 enzyme system

//Indications : Bronchial asthma (+receptor agonist)

Chronic obstructive lung diseases

Cardiogenic asthma

Sleep apnea syndrome


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//Adverse effect :

it has a narrow therapeutic window and its

therapeutic and toxic effects are related to its

plasma concentration.


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. Muscarinic antagonist :

Ipratropium bromide

Ipratropine

//Mechanism :act by blocking muscarinic receptors

esp. the M3

subtype , which responds

to this parasympathetic bronchial

constrictor tone .


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//Route of administration :metered dose inhaler

//Indication :

used as adjuncts to 2-adrenoceptoragonist in treatment of asthma and more

effective in vagus-induced asthma .

//Therapeutic note :synergism when administered with

2-adrenoceptor agonist.


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.Anti-inflammatory drug

Glucocorticoids include :

beclomethasone

budesonide

//Mechanism :

depress the inflammatory response in

bronchial mucosa thus diminish bronchial

hyperresponsiveness.


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Anti-inflammatory effect

Immunosuppressive effect

Increase the response to catecholamines

Adenoceptor-upregulation


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//Route of administration :

orally i.v

used for : severe asthma

status asthmaticus

metered dose inhaler

//Indications :

Because of the efficacy and safety of inhaled

corticosteroids, they are now routinely prescribed forpatients who require more than occasional inhalations of

agonist for relief of symptom.


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// Adverse effect: Oropharyngeal candidacies

it can be reduced by having patients gargle water

and spit after each inhaledtreatment.

Hoarseness(roughness)


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.Anti-allergic agents

i.e. mast-cell-stabilizers

cromolyn sodium

//Mechanism :

They appear to stabilize antigen-sensitized mast cell by

reducing calcium influx and subsequent release of

inflammatory mediators .


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On mast cells, for inhibition of the early response

to antigen challenge

On eosinophils, for inhibition of the inflammatoryresponse to inhalation of allergens


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//Route of administration :

metered dose inhaler of cromoly sodium

//Indications :

pretreatment with cromolyn blocks the

bronchoconstriction caused by antigen

inhalation ,by exercise, by aspirin, and by

a variety of cause of occupational asthma.


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// Adverse effect

Throat irritation

Cough

Mouth dryness

Chest tightness and so forth


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REFERENCES

LIPPINCOTT.

TRIPATHI.

WWW.pharmacology.com/phaame.htm

Mediconet.blogspot.com/2009/08/interactive_clinical pharmacology.

Wps.prenhall.com/chet_turley_undrstand pharm.

WWW.camargo pharma.com.


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Anti Asthmatics