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54 Cards in this Set

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What is histamine derived from?
histidine --decarboxylation--> histamine
What is the fate of metabolized histamin?
70%:methylation… 30%: oxydation by histaminase
Give the monamine precursors of the following: catecholamine, serotonin, melatonin.
catecholamine= tyrosin, serotonin=tryptophan, melatonin=tryptophan
Name the 4 cells that produce histamine.
mast cells, basohils, nerve cells (hypothalamus), enterochrmaffin-like cells (stomach fundus)
What triggers histamine release from mast cells?
IgE attaches to FcE receptor --> cross linked by multivalent antigen
What triggers non IgE mediated histamine relase "intrinsically"? (hint: SHIC)
Substance P, "histamine releasing factors from: (neutrophils, platelets, macrophages, and eosinophils), Interleukins, and complement derived anaphylotoxins
What triggers non IgE mediated histamine relase "extrinsically"?
opiates, (heroine, etc.), radiographic contrast containing iodine, and muscle relaxans (d-tubocurarine)
Why is it that scombroid fish poisoning occurs?
fish rich in histidine, where bacteria causes the decarboxylation to histamine, and then overwhelms the GI tract
Which histamine receptors are found in the CNS?
+++H1, ++H3, +H2, (+)H4
Which histamine receptors are found in the smooth muscle?
++H1, +H2, +H3(airway)
Which histamine receptors are found in the endothelial cells?
Which histamine receptors are found in the dendritic cells?
H1, H4
Which histamine receptors are found in the neutrophils, eosinophils, and monocytes?
Which histamine receptors are found in the parietal cells of the gastric mucosa?
Which histamine receptors are found in the heart cells?
atrium H1, atrium and ventricle H2, (H3)
Which histamine receptors are found in the uterus cells?
H1, H2
Bone marrow/hematopoietic cells
If not stated, which histamine receptor do you assume to be primarily present?
Which histamine receptor is effects the following? 1. Itching & pain… 2. Vasodilation… 3. Edema… 4. Tachycardia/vent contraction… 5. Bronchoconstriction… 6. Diarrhea… 7. Axonal reflex… 8. Gastic acid secretion… 9. Gastric acid inhibition… 10. CNS (post hyprothalamus) stimulation... 11. CNS inhibition... 12 bone marrow.
1. Itching & pain: H1>H3… 2. Vasodilation: H1>H2… 3. Edema: H1… 4. Tachycardia/vent contraction H2>H1… 5. Bronchoconstriction H1… 6. Diarrhea H1… 7. Axonal reflex: H1>H2=H3… 8. Gastic acid secretion: H2… 9. Gastric acid inhibition: H3… 10. CNS (post hyprothalamus) stimulation: H1>H2... 11. CNS inhibition: H3... 12 bone marrow: H4.
Which histamine receptor is usually involved in inhibition?
Which receptor superfamily do histamine receptors belong to?
T/F histamine GPCR are constituitively active.
TRUE, which means they can trigger downstream events without being stimulated
give the intracellular signaling pathway for H1 receptors.
Excite: cGMP, Ca, Phospholipase A2, C&D, inositol, diacyl glycerin, NFkB, cAMP, NOS
give the intracellular signaling pathway for H2 receptors.
Excite: cAMP, Ca, phospholiase C, portein kinase C, c fos
give the intracellular signaling pathway for H3 & H4 receptors.
Inhib: Ca, Map kinase, inhibition of cAMP
which histamine receptors are inhibitory and which are excitatory?
inhib: H3 H4… excit: H1 and H2
In terms of the clinical indication of 1st and 2nd generation antagonist drugs for H1, what is the difference? (hint: antiallergic, sedation, motion sickness)
1st generation: antiallergic, sedation, motion sickness… 2nd generation: antiallergic
What is the primary clinical indication for H2 antagonists?
Lower gastric acid secretion (acid reflux, ulcer, gastritis)
What are the potential uses for H3 antagonists?
cognitive disfunction, such as ADHD, alzheimer's and schizophrenia
Which are more selective of the H1 antagonists, 1st or 2nd generation?
second… thus first generation H1 antagonists are used to treat for more disease than 2nd generation
Which can cross the blood-brain-barrier, H1 antagonist first generation or second? Can these BBB crossing drugs effect other receptors, such as serotonin or muscarinic?
H1 first generation… yes
name three H1-antagonist first generation drugs, which of these three is the fastest acting?
diphenhydramine, hydoxyzine and meclizine (meclizine is the fastest acting, 1-hr… the others are 2 hours)
Which first generation H1 antagonist is use to treat motion sicknes and vertigo? And which are used to treat allery?
meclizine=motion sickness… diphenhydramine and hydroxyzine = allergy
what is the duration of action for diphenhyramine, hydoxyzine and meclizine?
diphenhyramine 12 hr , hydoxyzine 24 hr and meclizine 8-24 hr
what are the 3 effects of H1 receptor antagonist for first generation?
antiallergic, antiinflammation, decreased neurotransmission (sedation)
Name the other receptors H1 receptor antagonist binds to.
Muscarinic , alpha adrenergic , serotonin , cardiac ion channels
what are the effects that an H1 receptor antagonist has when bound to the following receptors: Muscarinic , alpha adrenergic , serotonin , cardiac ion channels
Muscarinic (dry mouth, urinary retention, sinus tachycardia), alpha adrenergic (hypotention, dizziness), serotonin (increased appetite), cardiac ion channels (prolonged QT interval and arrythmias)
what is the benefit of 2nd generation H1 receptor antagonist?
more specificity: primarily only binds to H1 receptors and doesn't cross the BBB --> used antiallergic and antiinflammatory (with decreased sedation)
name 3 second generation H1 receptor antagonist. What is the main indication for these drugs?
cetirizine, loratadine, fexofenadine… allergy
What is the onset of action and duration for cetirizine, loratadine, fexofenadine
cetirizine (1 hr), loratadine (1 hr), fexofenadine (2 hrs)… all are 24 hour duration
which drug is a histamine release inhibitor?
cromolyn sodium
Why is cromolyn sodium only used topically (i.e., inhaler, nasal spray, eye drops or oral for GI allergies)?
Cromolyn is poorly absorbed
What is the mechanism of action for cromolyn sodium?
cromolyn sodium inhibits delayed chloride channels by stabilizing the membrane of mast cells, nerves (of airway) and eosinophils
What is the indication for cromolyn?
prevents symptoms of allergic rhinoconjunctivitis… NOT USED FOR ASTHMA - steroids are used for this.
Name a physiologic histamine antagonist.
epinephrine… epi-pen
name 3 H2 receptor antagonist
ranitidine, famotidine, cimetidine (don't use this)
Which acid secretin is inhibited, nocturnal or meal stimulated do H3 receptor antagonists?
60-70% of nocturnal acid secretion
which cells do ranitidine, famotidine, cimetidine (H2 antagonists) effect?
H2 antagonists block the histamine (released by enterochromaffin cells) from stimulating parietal cells, also gastrin release in the presence of H2 block that down regulates parietal cells' release of acid
what is the normal pathway for acid secretion in the stomach?
gastin is realeased by gastrin releasing cells, which stimulates parietal cells to secretion acid, also gastin stimulates enterochromaffin cells to secret histamine, which will also cause parietal cell to secrete acid
Which types of drugs are now used to Rx peptic ulcer disease and prevent stress related bleeding from gastritis?
proton pump inhibitors
Which of the H2 antagonist cause most adverse side?
Name 4 adverse side effects seen in H2 antagonists.
CNS: halucinations, aggitation, confusion… Hyperprolactinemia (cimetidine), bradycardia and hypotension if infused rapidly.
Which H2 antagonist interferes with CYP pathways in the liver?
cimetidine and rantidine
T/F H2 antagonists should be adjusted in patients with renal failure.