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43 Cards in this Set
- Front
- Back
describe extrinsic causes of asthma
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caused by environmental factor- usually called allergic asthma becuase patients have pos responses to challenge with specific antigens and inc IgE
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describe intrinsic causes of asthma
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attributed to pathophysiologic disturbances- no family hx, neg response to antigenic challenge, normal IgE
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Is asthma common?
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yes
more pediatric admissions than any other ds 55% inc from 1982 to 1996 |
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Early/immediate symptoms of asthma?
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bronchoconstriciton
vascular leak HA proteases leukotrienes C4 and D4 prostaglandins |
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Late/sustained symptoms of asthma?
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TH2 cytokines- GM-CSF, IL 3, 4, 5, 9, and 13
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How many asthmatics have identifiable allergies?
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large percentage of adults don't
50% of kids don't |
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give examples of precipitants to asthma attacks
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viral URT infection
exercise/rapid respiration cold air chemicals (sulfur dioxide) |
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What causes airway hyperactivity?
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inflammation of airway mucosa
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acute stage of airway inflammation
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early recruitment of cells to airway
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sub-acute stage of airway inflammation
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recruited and resident cells activated to cause more persistent inflammation
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chronic stage of airway inflammation
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persistent level of cell damage and ongoing repair; permanent abnormalities in airway
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What is of more benefit, drugs that only target bronchoconstriction or drugs that more broadly address inflammation
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drugs that more broadly address inflammation
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What are the two types of asthma drugs
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short term relievers- relax airway sm mm
long term relievers- anti-inflammatory |
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Do aerosol treatments work for most patients
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over 90% can be managed by them alone
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this inhaler usually contains a large-column holding chamber (spacer) that fits between the inhaler and mouth; the inhaler discharges into it, and the patient inhales from it
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metered-dose inhaler
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this inhlaer is not as cheap or portable, but doesn't require hand/breathing coordingation
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nebulizer
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this inhaler was developed as an alternative to CFC propellants
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dry powder inhaler
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What is the preferred therapy for bronchoconstriction?
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inhalation beta agonist
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What may regular use of beta agonist inhaler cause?
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potentiate bronchial hyperresponsiveness- tachyphylaxis with diminished beta2 receptors
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MOA of bronchodilators (5)
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1. relaxes sm mm;
2. inhibits release of bronchoconstricting agents; 3. inhibits microvascular leakage; 4. increases mucociliary transport; 5. beta agonists stimulate adenylyl cyclase --> inc sm mm relax |
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toxicity from bronchodilators?
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cardiac arrhythmias from beta-1 stimulation
possible tachyphylaxis or tolerance to beta agonists *beta2 selectives are usually safe |
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when can muscarinic antagonists be helpful?
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when patients are intolerant of inhaled beta agonists;
to enhance nebulized albuterol effect; role in COPD |
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what limits the quantity of muscarinic antagonists given
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systemic adverse effects (urinary retintion, tachycardia, loss of accomodation, agitation)
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muscarinic antagonist MOA
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blocks action of ACh from parasympathetic neurons --> blocks bronchoconstriction and icreased secretion of mucous that accompanies vagal activity
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How many asthmatics are tx with methylxanthines
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less than 1%, still used because of high compliance
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methylxanthine MOA
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antagonism of adenosine receptors --> relaxes bronchial sm mm;
stimulates CNS and cardiac mm; diuretic; inhibits phosphodiesterases (inc cAMP); effects Ca conc; may be anti-inflammatory |
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side effects of methylxanthines
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arousal, tremor, convulsions, tachycardia, arrythmias, weak diuretic
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how are methylxanthines administered
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are readily absorbed after oral, rectal, and parenteral administration- take your pick
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What is the major drug interaction of methylxanthines
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interacts with many; but major is with macrolide antibiotics- can cause build up of theophylline due to inhibition of P450 --> seizures
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is the TI of methylxanthines high or low?
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low
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give 4 reasons to use corticosteroids
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1. anti-inflammatory
2. reduces bronchial reactivity and increases airway caliber 3. reduces frequency of asthma attacks 4. potentiates effects of beta agonists |
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corticosteroid MOA (3)
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1. inhibits eosinophil-induced inflammation
2. inhibits cytokine production 3. inhibits release of arachidonic acid from cell membranes --> dec prostaglandins and leukotrienes |
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Adverse effects of inhaled corticosteroids
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minimal:
cataracts dec. bone density oral candidiasis |
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adverse effects of oral corticosteroids
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severe:
wt gain iatrogenic Cushing's syndrome adrenal suppression |
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What drugs are used for prophylaxis only?
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cromolyn and
nedocromil (ne-dOk'-ra-mill) |
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How are cromolyn and nedocromil used?
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insoluble salts used with inhalers --> plasma conc peaks in 15 minutes --> excreted unchanged
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What types of asthma do cromolyn and nedocromil block?
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antigen and exercise-induced asthma
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What happens when cromolyn and nedocromil are used regularly for more than 2-3 months?
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reduce bronchial hyperactivity
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What's more potent: cromolyn, inhaled glucocorticoids, or nedocromil
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inhaled glucocorticoids > nedocromil > cromolyn
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cromolyn and nedocromil MOA (5)
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1. inhibit delayed Cl channes
2. reduce mast cell degranulation 3. inhibit release of infl mediators 4. block effects of chemotactic peptides 5. inhibit IgE production |
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When are leukotriene pathway inhibitors used?
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aspirin or exercise induced asthma
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How are leukotriene pathway inhibitors administered?
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orally
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leukotriene pathway inhibitors MOA
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inhibit synthesis or action --> no LTB4 (neutrophil chemoattractant); LTC4 or LTD4 (bronchoconstriction, reactivity, mucosal edema, and hypersecretion)
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