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44 Cards in this Set
- Front
- Back
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What are the main cells that contain histamine?
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Mast Cells
Basophil Cells Certain Neurons in CNS Enterchromaffin-like cells in GI |
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Where are there high concentrations of histamine containing mast cells and basophil cells?
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Lungs
Skin GI tract |
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What stimulates histamine release? (2)
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Mechanical Stimulation
Chemical Stimulation -bacterial toxins -certain drugs |
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Where are H1 receptors located?
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Smooth Muscle
Vascular Endothelium Sensory Neurons Heart |
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What effect does histamine have on bronchial smooth muscle?
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bronchoconstriction
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Are H1 receptor blockers effective in treating/preventing bonchoconstriction in pt's with asthma?
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Not alone
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What effect does histamine have on arterioles?
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Vasodilation ---> Leaky
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How does histamine cause edema?
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Increases vascular permeability
↓ Makes vessels leaky |
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What effect may histamine have on BP?
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↓BP
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What effect does histamine have on mucocutaneous nerve endings?
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Depolarizes --> Itching/irritation
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Why were 2nd generation H1 receptor blockers developed?
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2nd generation developed to reduce the side effects caused by 1st generation H1 receptor blockers
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1st generation H1 Blockers
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Diphenhydramine
Meclizine |
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2nd generation H1 Blockers
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Fexofenadine
Loratadine |
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Diphenhydramine
Meclizine |
1st generation H1 Blockers
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Fexofenadine
Loratadine |
2nd generation H1 Blockers
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What is the role of histamine in allergic rhinitis?
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NO induced vasodilation and Increased vascular permeability
↓ Nasal Congestion |
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What is the main histamine receptor involved in allergic rhinitis?
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H1 receptor
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What types of effects does histamine have on the skin?
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NO induced VD--> red spot
Vessel leakage--> Wheal Axon reflex - vasodilation --> Flare |
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What is the main receptor involved in acute uticaria?
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H1 receptor
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Will H1 blockers treat the hypotension and bronchoconstriction involved with anaphylaxis?
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NO, USE EPI
Antihistamines can be used w/ EPI but NEVER ALONE |
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How do antihistamines act as sedatives?
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CNS depression
↓ sedation |
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What receptors in the vestibular apparatus activate the vomit center?
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H1 , Muscarinic
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What receptors do antihistamines block to stop motion sickness/vomiting?
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H1, Muscarinic
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Can 1st generation antihistamines cross the BBB?
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YES
this is why they have so many side effects (sedative, antiemetic, antimuscarinic) |
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Why do 2nd generation antihistamines have so few side effects?
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CAN'T CROSS BBB
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What other drug should antihistamines be given with treat angioedema?
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EPI
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"Antihistamines ____ better than reverse symptoms"
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prevent symptoms
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What drug can be used topically for temporary relief of puritis and pain associated with sunburn, minor cuts and scrapes, insect bites, etc..?
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Diphenyhydramine
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Which antihistamines can be used for sedation/hyposis ----> sleep aids
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1st generation antihistamines
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Which antihistamines can be used for motion sickness and the common cold?
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1st Generation Antihistamines
**Anticholinergic Effects** |
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Which antihistamines have adverse effects such as sedation, dizziness and fatigue?
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mainly 1st generation antihistamines
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which antihistamine should be avoided while driving becuase it produces an effect similar to driving with a BAC of 0.05 - 0.1%?
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Diphenhydramine
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Which antihistamines cause Atropine-like effects?
(dry mouth, blurred vision, dry eyes, urinary retention/hesitancy) |
1st generation antihistamines
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Which antihistamine has teratogenicity?
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Meclizine
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When used topically, a side effect of antihistamine creams is _______
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contact dermatitis
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Acute antihistamine poisoning looks like _______ poisoning
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Atropine poisoning
(convulsions, hallucinations, excitment, Ataxia, fixed dilated pupils, flushed face, dry-mouth, urinary retention, fever) |
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A patient who you have recently prescribed an antihistamine to complains of falling and convulsions. Upon examination they have fixed dilated pupils, dry-mouth, a flushed face and state they haven;t peed in two days. What are you thinking
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Antihistamine poisoning --> mimics atropine poisoning
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What drugs can you give to treat symptoms of atropine poisoning?
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for convulsions --> diazepam
for anticholinergic effects --> physostigmine |
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What is physostigmine's MOA in treating antihistamine poisoning?
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Acetocholinesterase Inhibitor (AChEI)
(inhibits breakdown of ACh from muscarinic receptor) |
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This is given as a nasal spray or opthalmic ointment (allergic conjunctivitis) to treat or prevent seasonal rhinitis. It inhibits mast cell release of histamine
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Cromolyn
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How do α-blockers help treat rhinitis?
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Vasocontrict nasal passages --> ↓congestion
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What are 2 α-blockers that help treat rhinitis?
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pseudoephederine
phenylepherine |
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These agents are used to treat seasonal rhinitis. They are effective, but expensive. Improves itching, rhinorrhea and congestion. Not much help for allergic conjunctivitis. Work best if started before allergy season.
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Intranasal corticosteroids (INC)
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Leukotriene inhibitor used for seasonal rhinitis
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Montelukast
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