pharm I

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  1. Histamine H1 receptors are located where
    many tissues (vascular, respiratory)
  2. activation of H1 receptros by histamine or histamine-like agents (2-methylhistamine) have affects on ..
    • cardiovascular system
    • extravascular smooth muscle
  3. how does activation of H1 receptors impact cardio vascular system
    • vasodilation causes reduction of perph resistance and decrease in BP
    • increased capillary permeability & formation of edema
  4. where are H2 receptors located
    parietal cells of stomach mucosa
  5. activation of H2 receptors by histamine and H2 receptor agonist 4-methylhistamine may cause...
    • increase in gastric acid secretion
    • to a lesser extent - secretion in small and large intestine
  6. H3 receptors are where?
    presynaptic -- located in brain, plexus myentericus, and other neurons
  7. activation of H3 receptors...
    • associated w reduction of transmitter release of histamine, norepinephrine, serotonin, or acetylcholine
    • maybe by a decrease in calcium influx
  8. affects of histamine released in body can be reduced by administration of
    • physiologic antagonists¬†
    • release inhibitors
    • receptor antagonists
  9. describe the physiologic antagonists that can reduce the affects of histamine in the body
    • they act at different receptors and have smooth muscle actins opposite to those of histamine
    • important in systemic anaphylaxis induced by histamine (epinephrine)
  10. describe the release inhibitors that reduce the affects of histamine in the body
    they reduce the degranulation of mast cells that result from IgE binding to the mast cells during alergic responses (cromolyn -- reduces bronchospasm)
  11. H1 receptor antagonists
    drugs that competitively block the actions of histamine at the H1 receptors
  12. H1 antihistamines are used in...
    • allergic reactions (new blockers with no sedative action are used for treatment of allergic rhinitis and utricaria)
    • prevention of motion sickness
    • fight nausea and vomiting of pregnancy
  13. terfenadine
    • H1 antihistamine
    • gives antiallergic reaction, lower sedation
  14. cyclizine
    • H1 antihistamine
    • slight sedation, prevents motion sickness
  15. H2 receptor antagonists do what
    • reversibly and selectively compete w histamine at H2 receptor sites
    • most important action: reduce secretion of gastric acid stimulated by histamine
  16. cimetidine
    • H2 receptor antagonist
    • reduces gastric secretion by inhibits the cytochrome P450 and binds to androgen receptors
  17. nizatidine
    • H2 receptor antagonist
    • reduces gastric secretion with no side effects
  18. name 2 H1 receptor antagonists
    • terfenadine
    • cyclizine
  19. name 2 H2 receptor antagonists
    • cimetidine
    • nizatidine
Card Set:
pharm I
2013-10-27 20:19:28

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