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31 Cards in this Set
- Front
- Back
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Where is HISTAMINE found w/i the body?
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w/i GRANULES of Mast cells & Basophils
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what are the PHYSIOLOGICAL ROLES of Histamine
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-bronchiole constriction (H1)
-intestinal sm muscle constriction (H1) -nrv stimulation ->Pain & itching (H1) -lwrs BP (H2) -gastric HCL secretion (H2) -incr. capill permeability (H2) |
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Name some H1-BLOCKERS?
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-Diphenhydramine -allergies, motion sickness
-Hydroxyzine - allergies -Promethazine - motion sickness |
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Name some H2-BLOCKERS
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-Cimentidine
-Rantidine -Famotidine |
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Describe H1-receptors
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-present in endothelium, sm. muscle cells, and nerve endings
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Describe H2-receptors?
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-Gastric mucosa
-cardiac muscle cells -immune cells Gs-prot linked |
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Describe H3-receptors?
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*REDUCE transmitter release
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Describe H4-receptors?
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-Leukocytes (in BM & blood)
-"chemotactic effect" on eosinophils & mast cells |
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Which histamine receptors control Vasodilation w/i the CVS?
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BOTH H1 and H2
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What is unique about H1 & H2 mediated vasodilation in the CVS?
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H1= rapid/short-lived (via NO formation on endothelial cells)
H2 = slower/sustained (via cAMP on vasc sm muscle) |
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What are the direct effects of H2-receptors on the heart?
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- increased Contractility
- increased Pacemaker Rate (nb: baroreflexes HIDE effects) |
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Which Histamine receptor is responsible for histamine-induced EDEMA and Uticaria?
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H1-receptors
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What is the "TRIPLE RESPONSE" caused by an intradermal injection of histamine?
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1) localized red spot = direct vasodilatoin
2) brighter Red flush = indirect vasodilation 3) a Wheal = edema |
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What are other H1 "EXTRAVASCULAR" efffects?
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- contraction intestinal sm musc
-bronchoconstriction -powerful stimulant of sensory nrv endings (pain & itching) |
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Which generation H1-blockers are CARDIAC TOXIC?
And HOW? |
-early 2nd-GEN H1-blockers
(when given w/Keto-Itraconazole, or Macrolides) ---> inhibit CYP3A4 --> lrg levels of free antihistamine --> BLOCKS HERG K+ channels --> prevents REPOLARIZATION |
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What fruit juice inhibits CYP3A4?
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Grapefruit juice
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List some H2-BLOCKERS?
(hint: "-tidines") |
Cimetidine (Prototype) (~Tagamet)
Rantidine (~Zantac) Famotidine (~Pepcid) NIzatidine (~Nizatidine) |
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What are the primary clinical indications for H2-blockers?
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Treatment of ;
-Peptic Ulcers -Acute Stress Ulcers -GERD |
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What are some AE's for use of H2-blockers?
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*inhibiton of CYP3A4 (slows alt drug metab)
-gynecomastia -reduced sperm count -galactorrhea -crosses placental barrier |
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What are some uses for
H1-blockers? |
-relief of ALLERGIES
-prevention of MOTION SICKNESS & NAUSEA -SEDATION |
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How many serotonin receptors (5HT) are there?
-# that G-protein linked? -which is "ligand-gated"? |
7 serotonin (5-HT) receptors
- 6 are G-prot linked - 5HT-3 (in CNS) is ligand-gated |
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Whichserotfound in the GI system?
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HT2 = incr GI motility
HT4 = incr Ach release --> prokinetic effect |
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Which serotonin-receptor is found in the Cardiac system?
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HT-2 = constriction of LRG vessels (arts & veins)
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Which serotonin receptor is found in on Platelets &
that act in "aggregation"? |
HT-2A
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Summarize serotonin receptors and their sites of effect?
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GI = HT2,4
CVS = HT2 Platelets = HT2A CNS = HT3 |
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Which Seotonin receptor works in the CNS?
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HT3 = powerful stim of PAIN & ITCHING
= stim "vomitting center" |
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DOC for Migraine HA's ?
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Sumatriptan (-triptans)
- acts on 5HT-1D/1B - inhibits Trigeminal nrv - vasoconSTricts bld vessels in head |
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What are three HT-4 agonists that act as "prokinetic" agents in the GI?
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-Metoclopromide
-CISAPRIDE -Tegaserod ***ALL WITHDRAWN d/t AE's*** |
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PT w/ hyperthermia,, muscle rigidity, myoclonus. Potentially fatal syndrome? What is it and how does it work?
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"SEROTONIN Storm"
-overstim of 5-HT1a and 5HT-2 |
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DOC for treatment of "serotonin storm"?
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Cyproheptamide
- 5-HT2 receptor ANTAGonist |
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5-HT3 (serotonin receptor) is a popular site for preventing severe N/V s/p chemo......which drugs are used?
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Anti-Emetics (2HT-3 ANTAGonists)
("-setron") Odansetron Granisetron etc..... |
