Asthma and COPD Flashcards
What are the symptoms of chronic obstructive pulmonary disease (COPD)?
Cough, mucus hypersecretion, dyspnea (shortness of breath)
What causes COPD?
Air pollution, smoking and occupational exposures (firefighters, construction, asbestos)
What disorders does COPD include?
Chronic bronchitis (inflammation of the bronchi with mucus to plug airway and edema to narrow airway) and emphysema (destruction of alveolar structure causing airways to collapse during expiration and trap air) Irreversible
What is asthma characterized by?
Recurring episodes of hyper-responsiveness to stimuli that causes bronchoconstriction
Airway obstruction, air gets trapped in alveoli despite it not being damaged, inflammation, mucus secretion
Reversible
What are the symptoms of asthma?
Recurring episodes of cough, wheezing, tight chest and dyspnea (shortness of breath)
What are the two subtypes of asthma?
Extrinsic (allergenic) and intrinsic (non-allergenic)
What can happen if asthma is untreated?
Reversible asthma can lead to irreversible airway remodelling (increased muscle thickness, reducing size of airway) from the chronic inflammation
What causes airway remodelling?
Fibrosis (scar tissue), muscle hypertrophy (growth of cells)/hyperplacia (new cells), angiogenesis and mucus hypersecretion
What symptoms of asthma and COPD can be treated?
Excessive airway smooth muscle tone, inflammation, mucus plugging, pulmonary edema, cough?
What causes extrinsic (allergenic) asthma?
Environmental allergens (dust, mold, dander, food) trigger the plasma cells to produce antigen specific IgE antibodies IgE and/or antigens binding to mast cells result in degranulation and release of inflammatory mediators
What inflammatory mediators are released by mast cells?
Arachadonic Acid, Leukotrienes, Cytokines
What causes intrinsic (non-allergenic) asthma?
Triggered by anxiety, stress, cold air, dry air, exercise, viruses
May be caused by abnormalities in the autonomic regulation (Ach release) of airway function to increase responsiveness, innate immune system is involved.
What are the acute responses of asthma?
Bronchoconstriction (occurs in minutes) that is mediated by histamine, leukotrienes, prostaglandins directly from mast cell
What are the prolonged responses of asthma?
Vasodilation, mucus secretion, edema, bronchoconstriction (occurs in hours) from eosinophil and basophils
Lead to the hyperresponsiveness and airway remodelling
What does inflammation from inhaled irritants (smoke, air) cause?
Damages epithelial layer, causes them to shed, removing protective layer and allowing irritants to penetrate, exposure of sensory nerves which can activate and microvascular leaks and edema
Inflammation stimulates Ach release from cholinergic reflex, leading to inflammation
What are some examples of bronchodilators?
Beta2-adrenergic agonists, methylxanthines, anticholinergics, leukotriene modifiers
What neurotransmitters cause bronchodilation and bronchoconstriction?
Epinephrine on the beta-2 (SNS) causes bronchodilation
Acetylcholine on the M3 muscarinic (PNS) causes bronchoconstriction and increased secretion
What ion causes bronchoconstriction?
High intracellular Ca causes bronchoconstriction, low intracellular Ca causes bronchodilation
How does Ca cause bronchoconstriction?
Ach binding to M3 receptors activates PLC and Gq (DAG and IP3 hydrolysis) to increase cytoplasmic Ca
Ca-calmodulin activates myosin via MLCK which binds to actin which slides past and causes a contraction
Adenosine also activates PLC
How does Ca cause bronchodilation?
Activation of beta 2 activates Gs and adenylyl cyclase which converts ATP into cAMP and activates PKA which promotes Ca pumps to decrease cytoplasmic Ca and inhibits MLCK
What are some examples of beta-2 adrenergic agonists?
Albuterol, Salbutamol, Terbutaline (short acting), Salmeterol (long acting, 12 hours)
Come as inhalation and pill
How do beta 2 adrenergic agonists work?
Stimulate adenylyl cyclase which increases the formation of cAMP which acts to relax the airway smooth muscle (bronchodilation)
What is the drug of choice for acute asthma attacks?
Albuterol
What should be administered with beta 2 agonists?
Corticosteroids to improve the efficacy of the beta agonists and prevent the development of tolerance and desensitization by the beta 2 receptors
Which beta 2 agonists can be used in a severe asthma attack?
Subcutaneous injection of terbutaline or epinephrine (beta 1 and 2 agonist) along with corticosteroids
What are the adverse effects of beta 2 agonists?
Beta 1 receptors may get stimulated, causing tachycardia (increased dose)
Skeletal muscle tremor, tolerance
Insulin release
What are the drug interactions with beta 2 agonists?
Won’t be effective in patients taking propranolol (beta blocker)