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Pathopharm Final > Serotonin, Kinins, Histamine > Flashcards

Serotonin, Kinins, Histamine Flashcards

1
Q

Histamine is found in all tissues with highest concentrations in:

A

lung, skin, and intestinal mucosa.

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2
Q

Histamine is synthesized from what?

A

Synthesized from histadine

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3
Q

Where is histamine stored?

A
  • intracellularly
  • in vesicles complexed w/ heparin
  • principal sites: mast cells (tissue phagocytes) & basophils (blood phagocytes)
  • GI mucosa
  • nerve endings in certain brain areas
  • cells of rapidly growing or regenerating tissue
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4
Q

What leads to the release of histamine?

A

Allergic reactions – release is initiated in allergen-sensitized mast cells when an antigen bridges adjacent molecules of IgE attached to the cell surface.
Cellular injury (mechanical, thermal, radiation)
Drugs and other factors
morphine and other opioids (causing peripheral arteriolar and venous diliation)
succinylcholine
radio contrast media (iodine containing worse?)
vancomycin, anti-protozoal drugs

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5
Q

What is histamines general pharmalogical effects?

A
  • In general, histamine contracts many smooth muscles, (bronchi & gut)
  • powerfully relaxes others (fine blood vessels)
  • potent stimulus to gastric acid production
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6
Q

What are the histamine receptors and what are their effects?

A

effects mediated by 2 subtypes (H1 & H2)
H1: constrict bronchi & gut
H2: gastric acid secretion
both: vasodilation

H3 autoreceptor: inhibition of histamine release & synthesis; H2 antagonists can block → ↑histamine release
H4: immune system modulation (?)

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7
Q

histamine (increases/decreases) capillary permeability. How does it do this?

A

increases
endothelial cells shrink and separate
plasma proteins and fluid flow out of vessels
edema

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8
Q

How does histamine cause vasodilation?

A

action on histamine receptors on blood vessels rather than on innervating neurons

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9
Q

effect of histamine on bp can only be completely reversed by giving ______

A

both an H1 and H2 blocker

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10
Q

How does histamine affect the peripheral vascular resistance and SBP?

A

decreased peripheral vascular resistance
decreased systemic blood pressure (BP)

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11
Q

What are the H2 effects on BP? H1?

A

H1 effect – rapid, poorly sustained drop in BP
H2 effect – slow onset, well sustained drop in BP

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12
Q

What is the “Triple Response of Lewis”?

A

rxn to intradermal histamine (wheal & flare reaction)
red spot
wheal – d/t edema
flare or red flush – d/t stimulation of local axons which indirectly dilate neighboring arterioles

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13
Q

What are the GI effects of histamine?

A

increased secretion of gastric acid and pepsin (H2)
increased GI motility (H1)

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14
Q

What are the bronchial effects of histamine?

A

constriction (H1)
asthmatics are extremely sensitive

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15
Q

Histamine nerve ending (H1) effects:

A

pain
itch

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16
Q

Histamine appears to be a neurotransmitter in the CNS T/F

A

TRUE
H1 and H2

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17
Q

recently, a third subtype of histamine receptor has been found (H3) which may:

A

may be an autoreceptor which regulates release of histamine
may modulate cholinergic transmission in human airways

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18
Q

hyposecretion in response to histamine suggests:

A

pernicious anemia vs. other types of anemia
gastric carcinoma
atrophic gastritis

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19
Q

hypersecretion in response to histamine suggests:

A

duodenal ulcer
Zollinger-Ellison syndrome (pancreatic tumor – elevated gastric acid and pepsin in stomach)

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20
Q

One of the clinical uses of histamine is for dx of certain pathological conditions T/F

A

TRUE

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21
Q

Weak isotonic solution may be administered by inhalation to assess bronchial hyper-reactivity in patients with clinically stable chronic asthma

A

Histamine

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22
Q

All H1 receptor antagonist are true antagonist T/F

A

FALSE
All are actually inverse agonists, not true antagonists

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23
Q

Alkylamines

A

First Generation Antihistamines

  • Brompheniramine (Veltane)
  • Chlorpheniramine (Chlor-Trimeton)
  • Dexchlorpheniramine
  • Triprolidine (Combo Products only – Triacin-C w/ pseudoephedrine and codeine)
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24
Q

All first generation antihistamines have ____

A

All have marked potential for producing sedation, which is usually additive when administered with other CNS depressants

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25
Q

Ethanolamines

A

1st gen antihistamine:

  • Carbinoxamine (sedative effects)
  • Clemastine (Tavist-1)
  • Dimenhydrinate (Dramamine) (marked sedation potential)
  • Diphenhydramine (Benadryl)
  • Doxylamine (Unisom)
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26
Q

Carbinoxamine is a mild ____

A

anticholinergic

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27
Q

Clemastine also blocks at ___ receptors

A

muscarinic (anticholinergic)

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28
Q

Dimenhydrinate is a combination of

A

diphenhydamine and 8-chlorotheophylline (added to decrease sedation)

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29
Q

dimenhydrinate is used to treat ____

A

motion sickness

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30
Q

Diphenhydramine (Benadryl)

A

marked potential for producing sedation
used to treat motion sickness
also blocks at muscarinic receptors (anticholinergic)

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31
Q

Doxylamine (Unisom)

A
  • marked potential for producing sedation (causes the earliest onset of sleep of all antihistamines)
  • reduced latency to end of wakefulness, early onset of sleep.
  • OTC sleep aid
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32
Q

Ethylenediamines

A

1st generation antihistamines
Pyrilamine

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33
Q

Pyrilamine

A
  • in some OTC PMS products w/ caffeine & tylneol (Midol Complete)
  • in some OTC cough/cold products
  • weak inverse agonist that crosses BBB
34
Q

Pyrilamine crosses the BBB T/F

A

TRUE

35
Q

Phenothiazines

A

1st generation antihistamines
promethazine HCL

36
Q

Promethazine HCL also blocks at what other receptors other than histamine?

A

alpha adrenergic & muscarinic receptors

37
Q

Promethazine HCl

A
  • anti-emetic
  • also blocks alpha adrenergic & muscarinic receptors
  • marked sedation potential
  • PO tabs, syrup, suppositories, IV injection
38
Q

What are the 2 piperazine derivatives (1st gen antihistamines)?

A
  • Hydroxyzine (Vistaril): sedative and antipruritic
  • Meclizine (Antivert): for motion sickness, vertigo, Meniere’s syndrome
39
Q

_____ is used for Meniere’s syndrome

A

meclizine

40
Q

piperidines are both anti____ and anti_____

A

(antihistaminic/antiserotonergic)

41
Q

Cyproheptadine

A

First Generation Antihistamines
Piperidines (antihistaminic/antiserotonergic)
also blocks at serotonin receptors
may cause increase in appetite and weight gain

42
Q

Cyproheptadine may cause a decrease in appetite and wt loss T/F

A

FALSE
may cause increase in appetite and weight gain

43
Q

Phthalazinone

A

2nd generation antihistamines
Azelastine (Astelin)

44
Q

Azelastine (Astelin)

A

the first antihistamine nasal spray
used to treat symptoms of seasonal allergic rhinitis
get relief with first dose; lasts 12 hours
2 sprays per nostril BID
most common SE is bitter taste and drowsiness

45
Q

2nd generation antihistamines are (sedating/non-sedating)

A

non-sedating

46
Q

do 2nd gen antihistamines cross the BBB well?

A

do NOT cross the BBB well

47
Q

2nd gen antihistamines have what kind of antimuscarinic effects?

A

minimal

48
Q

what is the order of the potencies for the (2nd generation antihistamine) inverse agonist?

A

potency: desloratadine > cetirizine > loratadine > fexofenadine

49
Q

Loratadine (Claritin)

A

2nd gen antihistamine
main use is allergic rhinitis and other allergy symptoms
once daily dosing (half-life of primary active metabolite – desloratadine – is 27 hours)
fairly selective for H1 receptor

50
Q

Desloratadine (Clarinex)

A

Second Generation Antihistamine
a primary metabolite of Loratadine
potent inverse agonist at H1 receptors
uses same as Loratadine

51
Q

a primary metabolite of Loratadine

A

desloratadine

52
Q

active metabolite of hydroxyzine

A

cetirizine

53
Q

Cetirizine (Zyrtec)

A

2nd gen antihistamine
active metabolite of hydroxyzine
has mild sedating effects

54
Q

Fexofenadine (Allegra) is an active metabolite of what?

A

active metabolite of terfenadine (which was removed from market due to cardiotoxicity)

55
Q

Fexofenadine (Allegra) is a (1st gen/2nd gen) antihistamine

A

2nd gen

56
Q

H1 antagonist block effect of histamine on ____

A

smooth muscle

57
Q

H1 antagonist are fully effective for allergic reactions T/F

A

FALSE
Only partially effective for allergic reactions
Edema, rash, and itch are blocked very well.

58
Q

hypotension is caused by histamine acting at _____ receptors.

A

BOTH H1 and H2

59
Q

Are H1 antagonist effective for severe hypersensitivity reactions (anaphylaxis)?

A

NO
hypotension is caused by histamine acting at BOTH H1 and H2 receptors.
upper respiratory obstruction due to laryngeal edema is reduced very little (mediated by leukotrienes).
DRUG OF CHOICE FOR ANAPHYLACTIC REACTIONS IS EPINEPHRINE.

60
Q

drug of choice for anaphylactic reactions is _____

A

EPINEPHRINE!!

61
Q

Excessive doses of H1 antags may cause what in children?

A

excessive doses may cause excitation and CNS stimulation in children.

62
Q

H1 antags have antitussive effects especially ____

A

promethazine

63
Q

H1 antags have additive sedative effects with:

A

additive effects with alcohol, other CNS depressants
more likely in elderly patients
caution patients about driving, operating machinery, etc.
more likely in elderly patients

64
Q

what action a/w H1 antags reduces symptoms of motion sickness?

A

anticholinergic action

65
Q

What can prolong and intensify H1 antags anticholinergic effects?

A

MAOI

66
Q

Second generation H1 antagonists have little or no sedative properties which means what?

A
  • cross blood-brain barrier poorly
  • not anticholinergic
  • use for allergic rhinitis
  • in general, onset too slow for acute allergy
67
Q

The side effects of H1 antags are common but rarely serious T/F

A

TRUE

68
Q

excessive dryness is a AE of (1st gen/2nd gen) H1 antags

A

1st gen

69
Q

Loss of appetite, nausea, epigastric distress, etc. are AE of ____

A

H1 antags

70
Q

What are the cardiac AE of H1 antagonist?

A
  • arrhythmias
  • Rare: serious effects; arrest & death
  • Primarily if excessive dose
  • Syncope sometimes seen before severe arrhythmias, so discontinue at first sign of syncope!
71
Q

what is sometimes seen before severe arrhythmias a/w H1 antags? What should you do?

A

Episodes of syncope are sometimes seen before severe arrhythmias, so discontinue at first sign of syncope!

72
Q

what are the clinical uses of antihistamines?

A

(depends on the agent)

  • Allergic reactions (rhinitis or “hay fever”, hives, bee stings)
  • Motion sickness & vestibular disturbances
  • Sedative in OTC sleep Rx
  • past: generally C/I for asthma d/t drying bronchiolar secretions
73
Q

H2 antagonist also act as inverse agonist like H1 antagonist T/F

A

TRUE

74
Q

How do H2 atagonist act?

A

Inhibit action of histamine at parietal cell H2 receptors, causing a decrease in acid secretion (50% - 80%)

75
Q

H2 antagonist are all very similair in _____ ; their only real differences are in their _____

A

structure
miligram potency

76
Q

Cimetadine causes an increased risk of ______

A

gynecomastia (< 1%)

“Cimeta-tiddies”

77
Q

Cimetadine (and to a lesser extent Ranitidine) decreases metabolism of _____, _____, and ______ and so should not be used with these agents

A

warfarin, phenytoin and theophyllin

78
Q

What are the primary uses of H2 antagonist?

A
  • dyspepsia
  • GERD
  • gastric & duodenal ulcer d/t excess acid production
79
Q

H2 antagonist Use largely supplanted by the _____

A

proton-pump inhibitors in cases of severe excessive acid production

80
Q

how do H2 antags pricing compare to that of the PPIs?

A

Much lower cost than proton-pump inhibitors and all now available OTC

81
Q

What are the H2 antag agents?

A

Cimetidine (Tagamet)
Ranitidine (Zantac)
Famotidine (Pepcid)
Nizatidine (Axid)

82
Q
A

Pathopharm Final (8 decks)

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