Histamine & Antihistamine Flashcards Preview

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Flashcards in Histamine & Antihistamine Deck (34):
1

Histamine exerts its effects by what receptor type

G protein coupled membrane receptors

2

Histamine is what type of neurotransmitter

monoamine

3

name to other neurotransmitters in the same class as histamine

Ach & Serotonin

4

Histamine is stored

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

5

The highest to lowest histamine content can be found where

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

6

What three factors cause histamine to be released

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)

7

Name two pathways of histamine metabolism

***Methylation>degradation via monamine oxidase

Oxidation

8

How many Histamine receptors exist

four (H1, H2, H3, H4)

9

Which Histamine receptors are most important

H2>H1>H3>H4

10

H2 receptor stimulation by histamine results in

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

11

H1 receptor stimulation by histamine results in

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

12

H3 receptor stimulation is thought

inhibit release of histamine

*blocade of H3 receptros cause increase in histamine

13

Local Histamine response results in

Triple response of Lewis

14

Triple response of Lewis is characterized by

Red spots (dilation of cap.)

Flare (arteriolar dilation)

Wheal (edema, capillary leaking)

15

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

False it is effective in treating edema and pruitis only

16

Is ACUTE anaphlylaxis managed with antihistamines

NO! Epinephrine is effective in tx

17

H1 and H2 receptor ANTAGONIST act by

occupying receptors on effector cell membranes, WITHOUT initiating a response

*competitive inhibition and reversible

18

Do ANTIHISTAMINEs inhibit the release of histamine

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

19

H1-receptor antagonists are classified as

first generation and second generation antagonists

20

H1-first generation antagonists exert what type of effects

sedation
anticholinergic
serotonin activation
alpha-adrenergic activation

21

H1-receptor antagonist and CNS

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

22

H1-antagonist chemical class include:

Ethanolamine (Diphenhydramine, Dimenhydrinate)- EDD

Piperazine ( Hydroxyzine-antichol,sedative)

Phenothiazine (promethazine- sedative, N/V)

23

Name the therapeutic uses of H1-receptor antagonist

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

24

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

True

25

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

CNS- decr. alertness

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

CV- Tachy, prolonge QTc, heart block, dysrrhymias

26

H2-receptor antagonists MOA

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

27

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

No

28

What happens when chronic H2-receptor antagonists are discontinued

rebound hypersecretion of gastric acid

29

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

No

30

What are the three therapeutic uses of H2-receptor antagonists

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

Duodenal ulcer dx

OTC acid reflux

31

Cimetidine (Tagament) DOA

6 hours

32

Cimetidine precautions

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

Ranitidine (Zantac) DOA and precautions

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

34

**Famotidine (Pepcid) DOA and precautions

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