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Mediator Antagonists

Mediator Antagonists

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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