Asthma Flashcards
What are common symptoms of asthma?
coughing
Wheezing
Chest tightness
SOB
What are the general mechanisms responsible for asthma (the “immunologic disease”)?
1) obstructive lung disease = bronchoconstriction
2) inflammation of the airway wall = airways respond to inflammation by airway edema, mucus secretion..
How does mast cell sensitization occur?
(1) exposure to antigen will induce systemic generation of antibodies by B cells and TH2 helper cells
(2) IgE antibodies will become fixated on the surface of the mast cell
(3) When antigens bind the antibody, degranulation follows
What mediators do mast cells release?
Histamine
Proteases
Heparin
Leukotrienes
Prostaglandins
Platelet activating factor (PAF)
What are preformed vs. lipid-derived mast cell mediators?
Preformed = immediate onset = histamine, protease
Lipid-derived = slower onset but LONGER duration = heparin, leukotrienes, Prostaglandins, PAF
Which are potent bronchoconstrictors?
Lipid-derived mast cell mediators
What effects do histamine have?
Vasodilation
Vasopermeability
Itch
Cough
Bronchoconstriction
Rhinorrhea
How does the second mechanism (inflammation of the airway wall) come about?
Immune cells get recruited during asthmatic inflammation
Their mediators are inflammatory and cause injury/inflammation in the airways
What is non-allergic asthma?
Inhaled irritants induce bronchoconstriction
What are 3 major pathways for treating asthma?
(1) anti-IgE therapy
(2) target inflammation with beta2 agonists, leukotriene modifiers, corticosteroids, or theophylline, anti-IgE therapy
(3) target bronchoconstriction with beta2 agonists, leukotriene modifiers, muscarinic receptor antagonists, theophylline
What is an advantage of aerosol delivery of drugs?
Produces high local concentration in the lungs with low systemic delivery
What drugs is aerosol delivery the main route for?
Beta2 adrenergic receptor agonists
Glucocorticoids
What are glucocorticoids used for asthma?
Maintenance therapy = reduces inflammation
Administered prophylactically !!!
Does NOT relax airway SM though
What are some examples of inhaled corticosteroids?
Beclomethasone
Triamcinolone
Flunisolide
Fluticasone
Budesonide
Fluticasone + salmeterol
Budesonide + formoterol
What’s the MOA for ICS?
Target lung inflammation
What are some side effects of ICS?
Oropharygneal candidiasis
Dysphonia
Modest decreases in bone density
What second messenger promotes bronchodilation?
Increased cAMP
What effect do beta2 adrenergic agonists have?
Bronchodilation
Activation of the receptor stimulates Gs and increases cAMP to relax bronchial SM
What effects do beta2 agonists have on inflammatory cells?
Stimulation of beta2 receptors on mast cells leads to increased cAMP and decreased mast cell degranulation
Cytokines production is impaired
Immune cell function is inhibited
What is a potential problem of beta2 adrenergic agonists?
Desensitization can occur = prolonged stimulation leads to loss of responsiveness, receptor downregulation
What are beta2 receptor agonists used for?
Rescue therapy!
Relief of acute bronchospasm
What are examples of beta2 adrenergic agonists?
Metaproterenol
Albuterol
Salmeterol
Terbutaline
Which is a SABA and which is a LABA?
SABA = short acting beta2 agonist = albuterol
LABA = salmeterol
What are side effects associated with beta2 adrenergic agonists?
Tremor
Hypokalemia
Tachycardia
Anxiety
Insomnia
Palpitations
Compare SABAs versus LABAs.
SABAs = effective for rescue therapy and for preventing exercise-induced asthma
LABAs = used in combination with ICS
What is a concern with LABAs?
Can lead to beta2 adrenergic receptor desensitization, downregulation
How do muscarinic antagonists work?
Block vagal nerve mediated bronchoconstriction and bronchial secretions mediated by ACh on SM
What are important examples of muscarinic antagonists?
Ipratropium = only COPD
Tiotropium = both COPD + asthma
What are some side effects of muscarinic antagonists?
Dry mouth
Urinary retention
Constipation
Tachycardia
What are important examples of leukotriene modifiers?
Zileuton
Montelukast
Used prophylactically in treatment of mild asthma