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18 Cards in this Set
- Front
- Back
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H1 receptor
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Smooth Muscle
Endothelium Brain IP3/DAG 2nd messengers Pruritis Pain Vasodilation Vasc. Permeability Hypotension Flushing headache Tachycardia Bronchoconstriction Cough reflex |
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H2 receptor
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Gastric Mucosa
Cardiac Muscle Mast Cells Brain Inc. cAMP Gastric acid secretion hypotension flushing tachycardia Headache bronchodilation mucus production (airway) |
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Amines (morphine, turbocucraine) and histamine
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amines can displace histamine from the hep-protein complex within mast-cells
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Urticarial response
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via H1 receptor activation
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H3 receptors
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in presynaptic histaminergic neurons in brain
dec. cAMP prevents excessive bronchoconstrict, mediates pruritis, reduces acetylcholine release, peripheral pain sensitization |
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H1 receptor and av conductance
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reduces av conduction (though tachycardia through H2 receptor)
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GI smooth muscle
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H1 agonism causes contraction of GI smooth muscle, diarrhea
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second generation H1 anagonists
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more selective, so less anticholinergic activity, less sedation, less antiemetic action, hydrophilic so does not pass through BBB
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motion sickness
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OTC dramamine, compozone are first generation H1 antagonists. also can use diphenhydramine, promethazine, cyclizine, meclizine, which are even more effective if combined with ephedrine or amphetamine
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entholamines
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diphenydramine (benadryl), sedative, first generation H1 blocker
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ethylenediamines
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tripelennamine, mildly sedative, first generation h1 antagonist
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alkylamines
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first generation H1 antagonist, dont use in preggers. chlorpheniramine is mildly sedative, can act as an SSRI
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phenothiazines
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first generation h1 antagonist. promethazine, antiemetic with prominent sedative actions, do not use for kids under 2 years of age
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first generation piperazines
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hydroxyzine, used for chronic urticaria, causes sedation
teratogen cyclizine, meclizine--antiemetic. |
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first generation piperidines
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cyproheptadine, phenindamine-- both anti Histamine and anti5HT, causes drowziness and is definitely anticholinergic
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second generation piperidines
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fexofenadine-- active metbaolite of terfenadine, lower risk of arrthyrmia, no CNS adverse effect
loratadine (claritin)-- Cytp450 changes it to its active metabolite desloratadine |
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cetirizine hydrochloride
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second generation piperazine (h1 blocker)
may cause sedation in adults |
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grapefruit juice
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terfenadine and ioratadine is metabolized by cytp450. this, however, is inhibited by graprefruit juice
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