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Antihistamines Flashcards

1
Q

Major mediator of immediate allergic and inflammatory processes

A

Histamine

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2
Q

Histamine is a significant regulator of

A

Gastric acid secretion

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3
Q

Important neurotransmitter in the central nervous system

A

Histamine

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4
Q

In the skin, mucous membranes, lungs, blood vessels, histamine synthesis depends on

A

Mast cells

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5
Q

In circulating blood, histamine synthesis depends on

A

Basophils

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6
Q

In the gastric mucosa and stomach, histamine synthesis depends on

A

ECL cells

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7
Q

In the brain, histamine synthesis depends on

A

Histaminergic neurons

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8
Q

Histamine is sequestered and bound in cytoplasmic granules of

A

Mast cells and basophils

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9
Q

Histamine is produced and stored in the gastric mucosa in the vesicles of

A

ECL cells

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10
Q

Histamine is produced and stored in the CNS in the vesicles of the

A

Histaminergic neurons

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11
Q

Antigens/allergens bind to IgE antibodies on the surface of pre-sensitized

A

Mast cells and basophils

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12
Q

This causes the aggregation of high-affinity IgE receptors, thus triggering

A

Degranulation

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13
Q

Can affect rapid degranulation and the local release of histamine

A

Mast cell injury/damage

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14
Q

Endocrine stimulation of the ECL cells or neuronal stimulation of histaminergic neurons can trigger

A

Rapid histamine exocytosis

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15
Q

Many compounds can stimulate the release of histamines from mast cells directly, without prior

A

Sensitization

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16
Q

These molecules are typically

-Can displace histamine from cytoplasmic granules

A

Organic bases or basic peptides

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17
Q

IgE-mediated histamine release is a

A

Type I hypersensitivity response

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18
Q

In activated mast cells, re-exposure to the antigen/allergen causes the bound IgE receptors to

A

Cross-link

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19
Q

Histamine receptors resulting in the inhibition of adenylyl cyclases and a decrease in cAMP

A

H3 and H4

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20
Q

Histamine receptor resulting in increased IP3 and increased DAG

A

H1

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21
Q

Histamine receptor that causes activation of adenylylcyclases and increased cAMP

A

H2

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22
Q

Leads to induced depolarization of afferent nerve endings, leading to the sensation of itch and pain

A

Histamine stimulation of H1

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23
Q

Histamine serves as a neurotransmitter for histaminergic neurons by binding

A

H1, H2, and H3

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24
Q

Histamine functions in appetite suppression and satiety by binding

A

H1 and H3

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25
Q

Histamine functions in increased wakefulness by binding

A

H1 and H3

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26
Q

Histamine functions in modulation of neurotransmitter release by binding

A

H3

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27
Q

Histamine causes dilation of terminal arterioles, postcapillary venules and pre-capillary sphincters by binding H1 and causing vascular endothelial production of

A

Nitric Oxide (NO)

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28
Q

Histamine causes dilation of terminal arterioles, postcapillary venules and pre-capillary sphincters by binding H2, leading to

A

VSM cAMP production and relaxation

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29
Q

Histamine causes contraction of endothelial cells via

A

H1

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30
Q

Histamine stimulation of H1 permits the escape of fluid, plasma proteins, and immune cells from post-capillary venules, thereby causing

A

Edema and decreased local BP

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31
Q

In some vascular beds, caused constriction of veins, further promoting edema by binding H1

A

Histamine

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32
Q

In the heart, Histamine-mediated vasodilation and decreased systemic BP leads to the indirect affect of

A

Reflex tachycardia

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33
Q

A direct effect of histamine on the cardiovascular system is minor increases in the force and rate of cardiac contraction via

A

H2

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34
Q

Engorges local micro- vasculature with blood and allows immune cells access to the injury where they can begin to remove and repair damaged cells and begin to fight infection

A

Histamine-mediated vasodilation

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35
Q

Histamine (and other released cytokines) have chemotactic properties that facilitate

A

Leukocyte recruitment

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36
Q

Histamine action on local afferent axons allows for sensation of

A

Foreign object

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37
Q

Histamines affect can be seen on the skin and is called the

A

Triple response of Lewis

38
Q

Caused by histamine-mediated endothelial cell contraction and local edema formation

39
Q

Histamine binds H1, causing contraction of bronchial smooth muscle, resulting in

A

Bronchoconstriction

40
Q

Facilitates gastrin-induced acid secretion in the stomach

A

Hitsamine (via H2)

41
Q

Histamine causes contraction of intestinal smooth muscle via

42
Q

Histamine stimulates mucous secretion in the small and large intestines via

43
Q

Spoiled scombroid fish or meat; sardines; anchovies; fermented foods, are foods with high

A

Histamine content

44
Q

Vasodilation, increased capillary permeability, and edema in the nasal mucosa and surrounding tissues

A

Allergic rhinitis and conjunctivitis

45
Q

When the allergen is distributed systematically and there is mast cell degranulation and systemic vasodilation

A

Anaphylaxis

46
Q

What are strategies aimed at blocking histamine action?

A

Antihistamines and inhibitors of mast cell degranulation

47
Q

The antihistamines are only specific for

48
Q

Have no effect on histamine release from storage sites

A

Antihistamines

49
Q

Used prophylactically to inhibit mast cell degranultion

A

Cromolyn and Nedocromil

50
Q

Block Cl- channels thereby inhibiting Ca2+ mobilization and thus degranulation

A

Cromolyn and Nedocromil

51
Q

Low water solubility; poorly absorbed across GI tract; must be inhaled

A

Cromolyn and Nedocromil

52
Q

What is the main drug that counteracts histamine action?

-The mainstay of treatment of anaphylaxis

A

Epinephrine

53
Q

Neutral at physiologic pH; hydrophobic (lipid-soluble); readily enter CNS

-highly sedative

A

1st generation of H1 antihistamines

54
Q

Common components of OTC treatments for insomnia, motion sickness, nausea, and severe itching

A

1st generation of H1 antihistamines

55
Q

1st generation antihistamines are general

A

Short acting

56
Q

Ionized at physiologic pH; hydrophilic (lipid-insoluble); minor/no CNS distribution

A

2nd generation H1 antihistamines

57
Q

Lower/no anti sedative effects and no anti-emetic actions

-Highly selective

A

2nd generation H1 antihistamines

58
Q

2nd generation H1 antihistamines are generally

A

Longer lasting (12-24 hours)

59
Q

What are three examples of first generation H1 anti-histamines

A

Ethanolamines, ethylenediamines, and alkylamines

60
Q

The most popular example of an ethanolamine is

A

Diphenhydramine (Benadryl®)

61
Q

What is a major side effect of first generation anti-histamines

A

Dizziness and drowsiness

62
Q

What is the main example of an ethylenediamines?

A

Tripelennamine (PBZ ®)

63
Q

What are two common 2nd generation H1 anti-histamines?

A

Second-generation piperazines and piperidines

64
Q

What is an example of a second generation piperazine?

65
Q

A carboxylated hydroxyzine, slight entry into CNS; also formulated with the pseudoephidrine HCl

66
Q

What are the main side effects of Zyrtec?

A

Insomnia, elevated HR

67
Q

What is an example of a second generation piperidine?

68
Q

Claritin is metabolized by the hepatic

A

Cytochrome P450 system

69
Q

What are the two 3rd generation H1 anti-histamines?

A

Levocetirizine (Xyzal®), and Desloratadine (Clarinex®)

70
Q

The active R-enantiomer of cetirizine

-has greater potency and can be used at a smaller dose

A

Levocetirizine (Xyzal®)

71
Q

Active/major metabolite of Loratadine

  • drug action not influenced inhibitors of CYP
  • greater potency
A

Desloratadine (Clarinex®)

72
Q

What are three therapeutic applications of antihistamines?

A

Allergic reactions (1st, 2nd, 3rd generation H1), Motion sickness (1st), Antiemetics (1st)

73
Q

Mostly ineffective for the treatment of asthma

A

1st, 2nd and 3rd Generation H1 Antihistamines

74
Q

May play an adjuvant role in the treatment of systemic anaphylaxis or angioedema; but epinephrine treatment is critical

A

1st, 2nd and 3rd Generation H1 Antihistamines

75
Q

What are three adverse effects of H1 anti-histamines?

A

CNS toxicity, Drug interactions, anticholinergic effects

76
Q

1st generation H1 anti-histamines can cause?

-contraindicated for pregnant/nursing women, newborns, and young infant

A

CNS toxicity

77
Q

Dilated pupils, blurred vision, double vision (diplopia), dry eye, dry mouth, dry respiratory passages (sometimes inducing cough), and urinary retention or frequency are examples of the

A

Anticholinergic (antimuscarinic) effects of 1st generation H1 anti-histamines

78
Q

Overdosage of astemizole or terfenadine (2nd generation drugs) may induce

A

Cardiac arrhythmias

79
Q

Concurrent use of 1st generation drugs with alcohol or other CNS depressants produces an additive effect that can significantly impair

A

Motor skills

80
Q

concurrent use with drugs that inhibit hepatic CYP metabolic system can potentially increase the levels and toxicity of

A

1st generation drugs

81
Q

Inhibits multiple hepatic cytochrome p-450 (CYP) drug metabolism pathways; potential for adverse drug- drug interactions

-an H2 anti-histamine

A

Cimetidine (Tagamet®)

82
Q

Exhibits some CYP interference but < than cimetidine

-an H2 anti-histamine

A

Ranitidine (Zantac®)

83
Q

The most potent H2 anti-histamine

-no CYP interference

A

Famotidine (Pepcid)

84
Q

Hydrophilic; at therapeutic doses they do not enter CNS

A

H2 Antihistamines

85
Q

Highly specific; do not affect H1 or H3 receptor signaling

A

H2 antihistamines

86
Q

Treat uncomplicated gastroesophageal reflux disease (GERD) (aka heart burn or dyspepsia)

A

H2 antihistamines

87
Q

H2 antihistamines promote healing of

A

Gastric and duodenal ulcers

88
Q

Treat Zollinger-Ellison syndrome (caused by a hyper-gastrinsecreting tumor of the pancreas or duodenum)

A

H2 antihistamines

89
Q

Interference with hepatic cytochrome P450 metabolic pathways (CYP1A2, CYP2C9, CYP2D6, CYP3A4); potential increased ½-life of other drugs metabolized by these pathways

A

H2 antihistamines Cimetdidine and Ranitidine

90
Q

Can occur in patients with impaired renal or hepatic function using H2 antihistamines

A

Neurological effects

Immunity (33 decks)

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