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51 Cards in this Set
- Front
- Back
How is histamine made?
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histidine -> (histidine decarboxylase) -> histamine
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Where in the body is histamine in highest concentrations?
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lung
skin stomach gut |
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Name three places where histamine is stored?
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mast cells (tissue phagocytes) and basophils (blood phagocytes)
CNS mucosal layer of GI tract |
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The histamine content of most tissues is related to their ... content?
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mast cell content
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Why is histamine inert in mast cells?
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its stored in secretory granules and linked to proteoglycans
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How does histamine negatively modulate its own release?
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through H2 receptors on mast cells
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When the histamine content of mast cells is depreciated, how long does it take for the concentration to return to normal
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it can take weeks
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Are allergic reactions causing histamine release cytolytic?
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no
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Name 5 chemicals that cause chemical histamine release
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morphine
tubocurarine succinylcholine vancomycin (red man syndrome) radiocontrast |
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are chemicals causing histamine release cytolytic?
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no
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is energy required for histamine release mediated cellular injury
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no
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Give 5 states in which symptoms from histamine toxicity (headache, flushing, hypotension, and nausea) are also seen
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1. mastocytosis
2. myelogenous leukemia 3. gastric carcinoid tumors 4. food poisoning from spoiled scombroid fish 5. red wine consumption when people have reduced ability to degrade histamine |
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What superfamily of receptors do histamine receptors belong to
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7 transmembrane G protein-linked receptors
[like rhodopsin ;)] |
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receptor in sm mm, endothelium and brain
signals PLC --> IP3, DAG, NO, and PLA |
H1
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receptor in gastric mucosa, brain, cardiac muscle, mast cells
signals cAMP, inhibition of arachidonic acid release, Ca |
H2
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receptor in presynaptic, brain, myenteric plexus, peripheral neurons
signals Ca, inhibits cAMP |
H3
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receptor in bone marrow, peripheral hematopoietic cells
signals Ca, inhibits cAMP |
H4
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through what histamine receptors is vasodilation mediated?
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H1: endothelial cells
H2: vascular sm mm |
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through what histamine receptors is increased cardiac contractility and increased pacemaker rate mediated?
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H2
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Through what histamine receptor is contraction of intestinal sm mm and increased GI motility mediated?
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H1
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Histamine receptor involved with bronchoconstriction
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H1
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What may happen in anaphylactic pregnant women?
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may abort due to uterine contraction
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Histamine receptor involved in stimulant of sensory nerve endings- pain and itching
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H1
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Histamine receptor involved in stimulant of gastric acid secretion from parietal cells?
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H2
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Histamine receptor involved in triple wheal and flare response to intradermal histamine injection
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H1
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Name a physiologic antagonist that acts through a different receptor and opposes action of histamine?
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epinephrine
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Name two drugs that can inhibit histamine release from mast cells?
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cromolyn
nedocromil |
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histamine receptor antagonists act at which receptors?>
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H1 and H2, they are competitive
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Describe first generation antihistamines
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small --> cross BBB
cross react w/ other receptors available OTC sedation as side effect |
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Describe second generation antihistamines
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larger and lipophobic
more specific for H1 prescription only (except Claritin) non-sedating |
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chlorpheniramine (chlortrimeton)
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1st generation antihistamine
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clemastine
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1st generation antihistamine
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dimenhydrinate
(dramamine) |
1st generation antihistamine
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diphenhydramine
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1st generation antihistamine
(benadryl) |
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doxylamine
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1st generation antihistamine
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hydroxine
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1st generation antihistamine
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meclizine
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1st generation antihistamine
(antivert) |
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promethazine
(phenergan) |
1st generation antihistamine
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fexofenadine
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2nd generation antihistamine
(allegra) |
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cetirizine
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2nd generation antihistamine
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loratadine
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2nd generation antihistamine
(claritin) |
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Name two antihistamines used for sleep induction
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diphenhydramine
doxylamine |
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only antihistamine approved antitussive
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diphenhydramine
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antihistamine most widely used for Parkinson's disease
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diphenhydramine
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three antihistamines to treat vertigo/motion sickness
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meclizine (Antivert)
promethazine (Phenergan) dimenhydrinate (Dramamine) |
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When do antihistamines reach peak plasma concentration
When do antihistamines reach peak effectiveness |
2 hrs after oral administration
5-7 hrs after oral administration |
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All 1st generation and most 2nd generation antihistamines are metabolized by which hepatic cytochrome?
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P450
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Who eliminates antihistamines faster- adults or kids?
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kids
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Name two 2nd generation antihistamines taken off the market
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astemizole (hismanal)
terfenadine (seldane) |
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Name two antihistamines thought to be of lower risk to take during pregnancy
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dimenhydrinate
loratadine |
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Name four H2 receptor antagonists
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cimetidine (tagamet)
famotidine (pepcid) nizatidine (axid) ranitidine (zantac) |