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Pharmacology > Histamine & Antihistamine > Flashcards

Histamine & Antihistamine Flashcards

1
Q

Histamine exerts its effects by what receptor type

A

G protein coupled membrane receptors

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2
Q

Histamine is what type of neurotransmitter

A

monoamine

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3
Q

name to other neurotransmitters in the same class as histamine

A

Ach & Serotonin

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4
Q

Histamine is stored

A

mast cell (skin, lungs, and GI tract), and basophils in a complex with heparin

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5
Q

The highest to lowest histamine content can be found where

A

LSNS(AS)S

Lungs>skin(face)>nasal mucosa>stomach/Duodenum>skin (abdomen)>spleen

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6
Q

What three factors cause histamine to be released

A

Antigen-antibody complex (Mast/Baso–IgE>degranulation>release of Heparin

Drugs & Chemicals (tissue damage, dextran, Epi, Morphine, Meperidine, Succin, d-Tubocurarine)

Physical agents (Touch, Cold, Heat)

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7
Q

Name two pathways of histamine metabolism

A

***Methylation>degradation via monamine oxidase

Oxidation

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8
Q

How many Histamine receptors exist

A

four (H1, H2, H3, H4)

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9
Q

Which Histamine receptors are most important

A

H2>H1>H3>H4

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10
Q

H2 receptor stimulation by histamine results in

A 
increased cAmp
Increase Gastric acid secretion
CNS stimulation
Increase cardiac output
coronary vasodilation
bronchodilaiton
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11
Q

H1 receptor stimulation by histamine results in

A 
Increased cGmp
bronchoconstriction
coronary vasoconstriction 
decreased cardiac output
**pruitis and sneezing
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12
Q

H3 receptor stimulation is thought

A

inhibit release of histamine

*blocade of H3 receptros cause increase in histamine

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13
Q

Local Histamine response results in

A

Triple response of Lewis

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14
Q

Triple response of Lewis is characterized by

A

Red spots (dilation of cap.)

Flare (arteriolar dilation)

Wheal (edema, capillary leaking)

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15
Q

True or False, Histamine blockers of H1 receptors can treat bronchoconstriction and hypotension

A

False it is effective in treating edema and pruitis only

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16
Q

Is ACUTE anaphlylaxis managed with antihistamines

A

NO! Epinephrine is effective in tx

17
Q

H1 and H2 receptor ANTAGONIST act by

A

occupying receptors on effector cell membranes, WITHOUT initiating a response

*competitive inhibition and reversible

18
Q

Do ANTIHISTAMINEs inhibit the release of histamine

A

NO, they attach to receptors and prevent responses mediated by histamine

19
Q

H1-receptor antagonists are classified as

A

first generation and second generation antagonists

20
Q

H1-first generation antagonists exert what type of effects

A

sedation
anticholinergic
serotonin activation
alpha-adrenergic activation

21
Q

H1-receptor antagonist and CNS

A

Don’t use in children with seizure disorders
can potentiate ETOH
Good for motion sickness

22
Q

H1-antagonist chemical class include:

A

Ethanolamine (Diphenhydramine, Dimenhydrinate)- EDD

Piperazine ( Hydroxyzine-antichol,sedative)

Phenothiazine (promethazine- sedative, N/V)

23
Q

Name the therapeutic uses of H1-receptor antagonist

A

allergic rhinoconjunctivits, common cold, hay fever, anaphylaxis (itching, edema), motion sickness, sedative, pre-blood transfusions, N/V

24
Q

True or False, 1st generation H1-receptor antagonists have most of the side effects profile than 2nd generation H1-receptor antagonists

A

True

25
Q

Side effects of 1st gen. H1-recep. antagonists

A

CNS- decr. alertness

Anticholinergics- Dry mouth, blurred vision, urinary retention, impotence

CV- Tachy, prolonge QTc, heart block, dysrrhymias

26
Q

H2-receptor antagonists MOA

A

competitively and selectively inhibits binding of histamine to H2 receptors which decreases cAmp and gastric parietal cell activity (dec. hydrogen ions)

27
Q

Does H2-receptor antagonist influence pH of gastric fluid already present in stomach

A

No

28
Q

What happens when chronic H2-receptor antagonists are discontinued

A

rebound hypersecretion of gastric acid

29
Q

does H2-receptor antagonist effect lower esophageal sphincter tone or gastric emptying

A

No

30
Q

What are the three therapeutic uses of H2-receptor antagonists

A

Preop- increase pH of gastric fluid prior to induction (give 30 min before induction)

Duodenal ulcer dx

OTC acid reflux

31
Q

Cimetidine (Tagament) DOA

A

6 hours

32
Q

Cimetidine precautions

A

Inhibits P450
Decreases hepatic blood flow
Dysrhythmias and hypotension with rapid injection
Cross BBB- confusion, agitation, seizures
**Don’t give to pregnant or breast feeders

33
Q

Ranitidine (Zantac) DOA and precautions

A 
10 hours
give 60 minutes before induction
10x more potent than cimetidine
decreases hepatic blood flow
DOES NOT inhibit P450
34
Q

**Famotidine (Pepcid) DOA and precautions

A

10 hours
give 60 minutes prior to induction
30x more potent than cimetidine

Pharmacology (27 decks)

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