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Drugs Affecting Respiratory System. Antihistamines. Drugs that directly compete with histamine for specific receptor sites Two histamine receptors H 1 (histamine 1 ) H 2 (histamine 2 ). Histamine-mediated disorders Allergic rhinitis (hay fever, mould and dust allergies) Anaphylaxis

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Antihistamines
Antihistamines

Drugs that directly compete with histamine for specific receptor sites

  • Two histamine receptors

    • H1 (histamine1)

    • H2 (histamine2)


  • Histamine-mediated disorders

    • Allergic rhinitis (hay fever, mould and dust allergies)

    • Anaphylaxis

    • Drug fevers

    • Insect bite reactions

    • Urticaria (itching)


H1 antagonists are commonly referred to as antihistamines

  • Antihistamines have several properties

    • Antihistaminic

    • Anticholinergic

    • Sedative


Mechanism of action
Mechanism of Action

  • Block action of histamine at the H1 receptor sites

  • Compete with histamine for binding at unoccupied receptors

  • Cannot push histamine off the receptor if already bound


  • The binding of H1 blockers to the histamine receptors prevents the adverse consequences of histamine stimulation

  • Prevent smooth muscle contraction of the bronchial airways

  • Decrease mucus secretion

  • Prevent increase of vascular permeability



Indications
Indications than reversing them

  • Nasal allergies

  • Seasonal allergic rhinitis (hay fever)

  • Allergic reactions

  • Motion sickness

  • Sleep disorders

  • Also used to relieve symptoms associated with the common cold such as sneezing, runny nose (Palliative treatment, not curative)


Side effects
Side Effects than reversing them

  • Anticholinergic effects, most common

    • Dry mouth

    • Difficulty urinating

    • Constipation

    • Changes in vision

  • Drowsiness

    • Mild drowsiness to deep sleep


First generation
First generation than reversing them

  • Diphenhydramine (Benedryl )

  • Chlorpheniramine (Piriton)

  • Promethazine hydrochloride (Phenergan)


Second generation
Second generation than reversing them

  • Loratidine

  • Ceterizine/cetrizine

They are much less likely to have side effects of sedation and dry mouth



Decongestants
Decongestants or renal disease, hypertension, asthma, COPD, peptic ulcer disease

What is nasal congestion?

  • Excessive nasal secretions

  • Inflamed and swollen nasal mucosa

  • Primary causes

    • Allergies

    • Upper respiratory infections (common cold)


Two decongestant forms or renal disease, hypertension, asthma, COPD, peptic ulcer disease

  • Oral/systemic

  • Inhaled/topically applied to the nasal membranes


Topical nasal decongestants
Topical Nasal or renal disease, hypertension, asthma, COPD, peptic ulcer diseaseDecongestants

  • Adrenergics

  • Intranasal steroids


Mechanism of action1
Mechanism of Action or renal disease, hypertension, asthma, COPD, peptic ulcer disease

  • Adrenergics

    • Constrict small blood vessels that supply Upper Respiratory Tract structures

    • As a result these tissues shrink, and nasal secretions in the swollen mucous membranes are better able to drain

    • Nasal stuffiness is relieved


  • Nasal steroids or renal disease, hypertension, asthma, COPD, peptic ulcer disease

    • Anti-inflammatory effect

    • Work to turn off the immune system cells involved in the inflammatory response

    • Decreased inflammation results in decreased congestion

    • Nasal stuffiness is relieved


  • Adrenergics or renal disease, hypertension, asthma, COPD, peptic ulcer disease

    • Ephedrine hydrochloride

  • Intranasal steroids

    • Beclomethasone dipropionate


Side effects1
Side Effects or renal disease, hypertension, asthma, COPD, peptic ulcer disease

AdrenergicsSteroids

Nervousness Local mucosal dryness

Insomnia and irritation

Palpitations

Tremors

(systemic effects due to adrenergic stimulation of theheart, blood vessels, and CNS)


Oral decongestants
Oral decongestants or renal disease, hypertension, asthma, COPD, peptic ulcer disease

  • Not that effective

  • Have unwanted sympathomymetic effects

  • Pseudoephridine


Antitussives
Antitussives or renal disease, hypertension, asthma, COPD, peptic ulcer disease

  • Drugs used to stop or reduce coughing

  • What is cough? Respiratory secretions and foreign objects are naturally removed by the Cough reflex initiated by irritation of sensory receptors in the respiratory tract

  • Productive cough

    • Congested, removes excessive secretions

  • Nonproductive cough

    • Dry cough


Opioids or renal disease, hypertension, asthma, COPD, peptic ulcer disease

  • Suppress the cough reflex by direct action on the cough centre in the medulla

    Examples:

    • Codeine

    • Hydrocodone


Nonopioids or renal disease, hypertension, asthma, COPD, peptic ulcer disease

  • Suppress the cough reflex by numbing the stretch receptors in the respiratory tract and preventing the cough reflex from being stimulated

    Examples:

    • Dextromethorphan


Indications1
Indications or renal disease, hypertension, asthma, COPD, peptic ulcer disease

  • Used to stop the cough reflex when the cough is nonproductive and/or harmful


Expectorants
Expectorants or renal disease, hypertension, asthma, COPD, peptic ulcer disease

  • Drugs that aid in the expulsion (removal) of mucus/ bronchial secretions

  • Reduce the viscosity of secretions

  • Disintegrate and thin secretions



What happens in asthma

What happens in ASTHMA ? the tendency to cough is indirectly diminished


Asthma causes a narrowing of the breathing airways
Asthma causes a narrowing of the breathing airways the tendency to cough is indirectly diminished

  • The narrowing that occurs in asthma is caused by three major factors: inflammation, bronchospasm, and hyperreactivity.

  • In inflammation the bronchial tubes become red, irritated, and swollen

  • The muscles around the bronchial tubes tighten during an attack of asthma. This muscle constriction of the airways is called bronchospasm


  • In patients with asthma, the chronically inflamed and constricted airways become highly sensitive, or reactive, to triggers such as allergens, irritants, and infections.

  • Exposure to these triggers may result in progressively more inflammation and narrowing and this is called hyperreactivity


  • The combination of these three factors results in difficulty with breathing out, or exhaling.

  • As a result, the air needs to be forcefully exhaled to overcome the narrowing, thereby causing the typical "wheezing" sound.

  • People with asthma also frequently "cough" in an attempt to expel the thick mucus plugs.



Management of asthma
Management of asthma into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood

  • some drugs are given to treat acute asthma exacerbations

  • Some drugs are used as long term maintenance therapy


Bronchodilators

Bronchodilators into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood


Bronchodilators1
Bronchodilators into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood

  • Adrenoceptor agonists

  • Antimuscarinic bronchodilators

  • Xanthene derivatives –theophilline

  • Antileukotriene agents/Leukotriene receptor antagonists

  • Cromones


Adrenoceptor agonists
Adrenoceptor agonists into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood

  • Used during acute phase of asthmatic attacks

  • Quickly reduce airway constriction and restore normal airflow

  • Stimulate beta2-adrenergic receptors throughout the lungs


  • Selective beta into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood2 drugs

    • Stimulate only beta2-receptors

    • Commonly used

    • Example: salbutamol


Selective beta2 agonists
Selective beta2 agonists into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood

  • Salbutamol

  • Terbutaline

  • Salmeterol

  • Formeterol


Side effects2
Side Effects into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood

  • Tremor

  • Headache

  • Peripheral venous dilatation

  • Palpitations



Antimuscarinic bronchodilators anticholinergics
Antimuscarinic bronchodilators/ Anticholinergics into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood

  • Acetylcholine (ACh) causes bronchial constriction and narrowing of the airways

  • Anticholinergics bind to the ACh receptors, preventing ACh from binding

  • Ex-ipratropium bromide



Antileukotriene agents leukotriene receptor antagonists
Antileukotriene agents/Leukotriene receptor antagonists into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood

  • Montelukast

  • Zafirlukast


Mechanism of action2
Mechanism of Action into the bloodstream, and if very severe, carbon dioxide may dangerously accumulate in the blood

  • Leukotrienes are substances released when expose to a trigger, such as cat hair or dust, and starts a series of chemical reactions in the body

  • Leukotrienes cause inflammation, bronchoconstriction, and mucus production

  • Result: coughing, wheezing, shortnessof breath



Mast cell stablizers
Mast cell stablizers to receptors on cells in the lungs and in circulation

Sodium cromoglicate

  • Mechanism of action is not very clear, but known to affect on inflammatory mediated cells

  • Indicated in prophylaxis of asthma by inhalation


Preventers
Preventers to receptors on cells in the lungs and in circulation


Corticosteroids
Corticosteroids to receptors on cells in the lungs and in circulation

  • Very effective in asthma

  • Mechanism of action :

  • Enter cells where they combine with steroid receptors in cytoplasm

  • Inhibit inflammation/reduce synthesis of inflammatory mediators


Inhalers
Inhalers to receptors on cells in the lungs and in circulation

IN asthmatics inhalers are used to deliver drugs more effectively with minimal side effects

Relievers have to be taken when they get worsening of asthma

Preventers should be used daily for it to be effective

Patients should be clearly educated on this …


Oxygen therapy
Oxygen Therapy to receptors on cells in the lungs and in circulation

  • Oxygen therapy is the administration of oxygen as a medical intervention

  • Administration of oxygen at concentrations greater than that in room air ( 21%) to treat or prevent hypoxemia (not enough oxygen in the blood)


High concentration o 2 therapy
High concentration O to receptors on cells in the lungs and in circulation2 therapy

  • Concentrations up to 60%

  • Use in pneumonia and many other conditions


Low concentration o 2 therapy
Low concentration O to receptors on cells in the lungs and in circulation2 therapy

  • The concentration should not exceed 28%

  • Used in COPD

  • Improve the hypoxemia with out worsening existing CO2 retention



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