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Mediator Antagonists

Mediator Antagonists. Chapter 12. Mechanisms of inflammation in asthma. Types of asthma Extrinsic dependent on allergies Intrinsic shows no sensitization to allergens With both forms airway inflammation is evident causing bronchoconstriction, airway swelling, mucus secretion and obstruction.

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Mediator Antagonists

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  1. Mediator Antagonists Chapter 12

  2. Mechanisms of inflammation in asthma • Types of asthma • Extrinsic dependent on allergies • Intrinsic shows no sensitization to allergens • With both forms airway inflammation is evident causing bronchoconstriction, airway swelling, mucus secretion and obstruction

  3. Allergic response • Primarily involves mast cells and immunoglobin E • Lymphocytes (T cells) activated by an antigen result in the production of IgE • IgE binds to mast cells • Releases mediators of inflammation such as prostaglandins, leukotrienes, histamine, platelet aggregating factor, and cytokines

  4. Allergic response • Mediators from mast cell cause vascular leakage, bronchoconstriction, mucus secretion, and mucosal swelling • Once initiated the inflammatory response causes the release of eosinophils, neutrophils, and lymphocytes which increase the severity of the inflammation

  5. Disodium cromoglycate/Cromolyn sodium • Comes from the seeds of a plant Ammi visagna • Extract of khellin taken from here-originally used to treat colic • Prophylactic agent to prevent asthmatic reactions • Not related to any other drug category such as beta agonists, xanthines, or glucocorticoids

  6. Indications for use • Prophylactic management of asthma • Prevention of exercise induced asthma • For allergic rhinitis • Extrinsic asthma

  7. Mode of action • Prevents mast cell degranulation • Blocks release of chemical mediators • Must be used as a pretreatment • May work by preventing calcium from allowing the contraction of the filaments on the mast cell which release the mediators • Does not work as an antagonist on the mediators themselves • Does not affect alpha or beta receptors

  8. Mode of action cont. • Does not prevent antibody formation, the attachment of IgE, and the combination of antibody-antigen reactions-only prevents the release of the mediators

  9. Dosage and administration • Spinhaler (dry powder inhaler)-can be irritating and cause coughing or bronchoconstriction. May need beta 2 agonist prior to or after tx. • Ampule for nebulization (20 mg/2ml). Brand names Aarane or Intal • MDI • Nasal solution(Nasalcrom)

  10. Side Effects • Safe drug • Dry powder causes throat irritation, hoarseness, dry mouth • Nebulizers associated with cough, wheezing, sneezing

  11. Clinical Applications • Drug is only prophylactic and should not be used during acute bronchospasm. No bronchodilating action. • No affect on the adrenal system and can’t be used as replacement for corticosteroids • May take 2 to 4 weeks for improvement in patient’s symptoms

  12. Nedocromil sodium (Tilade) • Cromolyn sodium type drug • Prophylactic therapy for asthma management • Inhibits mast cell mediator release • Can inhibit eosinophil activity

  13. Leukotrienes • Production from leukocytes. • Release of leukotrienes during inflammatory reaction causes narrowed airways, excessive mucus production, airway inflammation

  14. Role of leukotrienes in asthma • Leukotrienes originally called SRSA • Released by inflammatory cells • Directly contract airway smooth muscle • 1000 x more potent than histamine in causing bronchial contraction and the contraction lasts longer • Also stimulate hypersecretion of mucus

  15. Leukotrienes • Also stimulate vascular permeability which causes airway swelling

  16. Antileukotriene therapy • Inhibit the production and block the action of leukotrienes • Two main classes: leukotriene synthesis inhibitors and leukotriene receptor antagonists

  17. Pharmacologic agents • Montelukast (singulair) • Leukotriene receptor antagonist • Blocks leukotrienes at receptor site • Improves airway obstruction, may keep episodes from worsening in chronic asthma

  18. Pharmacologic agents • Zafirlukast (Accolate) • Receptor antagonist used in the tx of chronic asthma • Inhibits bronchoconstriction.

  19. Pharmacologic agents • Zileuton (Zyflo)Inhibits formation of leukotrienes • Inhibits bronchoconstriction caused by various allergens

  20. Side effects • Accolate(Zafirlukast)-headache, nausea, diarrhea, abdominal pain, infection • Zileuton(Zyflo)-headache, abdominal pain, loss of strength, stomach upset • Montelukast(Singulair)- does not have these side effects

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