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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
Histamine functions in increased wakefulness by binding
H1 and H3
26
Histamine functions in modulation of neurotransmitter release by binding
H3
27
Histamine causes dilation of terminal arterioles, postcapillary venules and pre-capillary sphincters by binding H1 and causing vascular endothelial production of
Nitric Oxide (NO)
28
Histamine causes dilation of terminal arterioles, postcapillary venules and pre-capillary sphincters by binding H2, leading to
VSM cAMP production and relaxation
29
Histamine causes contraction of endothelial cells via
H1
30
Histamine stimulation of H1 permits the escape of fluid, plasma proteins, and immune cells from post-capillary venules, thereby causing
Edema and decreased local BP
31
In some vascular beds, caused constriction of veins, further promoting edema by binding H1
Histamine
32
In the heart, Histamine-mediated vasodilation and decreased systemic BP leads to the indirect affect of
Reflex tachycardia
33
A direct effect of histamine on the cardiovascular system is minor increases in the force and rate of cardiac contraction via
H2
34
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
Histamine-mediated vasodilation
35
Histamine (and other released cytokines) have chemotactic properties that facilitate
Leukocyte recruitment
36
Histamine action on local afferent axons allows for sensation of
Foreign object
37
Histamines affect can be seen on the skin and is called the
Triple response of Lewis
38
Caused by histamine-mediated endothelial cell contraction and local edema formation
A wheal
39
Histamine binds H1, causing contraction of bronchial smooth muscle, resulting in
Bronchoconstriction
40
Facilitates gastrin-induced acid secretion in the stomach
Hitsamine (via H2)
41
Histamine causes contraction of intestinal smooth muscle via
H1
42
Histamine stimulates mucous secretion in the small and large intestines via
H2
43
Spoiled scombroid fish or meat; sardines; anchovies; fermented foods, are foods with high
Histamine content
44
Vasodilation, increased capillary permeability, and edema in the nasal mucosa and surrounding tissues
Allergic rhinitis and conjunctivitis
45
When the allergen is distributed systematically and there is mast cell degranulation and systemic vasodilation
Anaphylaxis
46
What are strategies aimed at blocking histamine action?
Antihistamines and inhibitors of mast cell degranulation
47
The antihistamines are only specific for
H1 and H2
48
Have no effect on histamine release from storage sites
Antihistamines
49
Used prophylactically to inhibit mast cell degranultion
Cromolyn and Nedocromil
50
Block Cl- channels thereby inhibiting Ca2+ mobilization and thus degranulation
Cromolyn and Nedocromil
51
Low water solubility; poorly absorbed across GI tract; must be inhaled
Cromolyn and Nedocromil
52
What is the main drug that counteracts histamine action? -The mainstay of treatment of anaphylaxis
Epinephrine
53
Neutral at physiologic pH; hydrophobic (lipid-soluble); readily enter CNS -highly sedative
1st generation of H1 antihistamines
54
Common components of OTC treatments for insomnia, motion sickness, nausea, and severe itching
1st generation of H1 antihistamines
55
1st generation antihistamines are general
Short acting
56
Ionized at physiologic pH; hydrophilic (lipid-insoluble); minor/no CNS distribution
2nd generation H1 antihistamines
57
Lower/no anti sedative effects and no anti-emetic actions -Highly selective
2nd generation H1 antihistamines
58
2nd generation H1 antihistamines are generally
Longer lasting (12-24 hours)
59
What are three examples of first generation H1 anti-histamines
Ethanolamines, ethylenediamines, and alkylamines
60
The most popular example of an ethanolamine is
Diphenhydramine (Benadryl®)
61
What is a major side effect of first generation anti-histamines
Dizziness and drowsiness
62
What is the main example of an ethylenediamines?
Tripelennamine (PBZ ®)
63
What are two common 2nd generation H1 anti-histamines?
Second-generation piperazines and piperidines
64
What is an example of a second generation piperazine?
Zyrtec
65
A carboxylated hydroxyzine, slight entry into CNS; also formulated with the pseudoephidrine HCl
Zyrtec
66
What are the main side effects of Zyrtec?
Insomnia, elevated HR
67
What is an example of a second generation piperidine?
Claritin
68
Claritin is metabolized by the hepatic
Cytochrome P450 system
69
What are the two 3rd generation H1 anti-histamines?
Levocetirizine (Xyzal®), and Desloratadine (Clarinex®)
70
The active R-enantiomer of cetirizine -has greater potency and can be used at a smaller dose
Levocetirizine (Xyzal®)
71
Active/major metabolite of Loratadine - drug action not influenced inhibitors of CYP - greater potency
Desloratadine (Clarinex®)
72
What are three therapeutic applications of antihistamines?
Allergic reactions (1st, 2nd, 3rd generation H1), Motion sickness (1st), Antiemetics (1st)
73
Mostly ineffective for the treatment of asthma
1st, 2nd and 3rd Generation H1 Antihistamines
74
May play an adjuvant role in the treatment of systemic anaphylaxis or angioedema; but epinephrine treatment is critical
1st, 2nd and 3rd Generation H1 Antihistamines
75
What are three adverse effects of H1 anti-histamines?
CNS toxicity, Drug interactions, anticholinergic effects
76
1st generation H1 anti-histamines can cause? -contraindicated for pregnant/nursing women, newborns, and young infant
CNS toxicity
77
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
Anticholinergic (antimuscarinic) effects of 1st generation H1 anti-histamines
78
Overdosage of astemizole or terfenadine (2nd generation drugs) may induce
Cardiac arrhythmias
79
Concurrent use of 1st generation drugs with alcohol or other CNS depressants produces an additive effect that can significantly impair
Motor skills
80
concurrent use with drugs that inhibit hepatic CYP metabolic system can potentially increase the levels and toxicity of
1st generation drugs
81
Inhibits multiple hepatic cytochrome p-450 (CYP) drug metabolism pathways; potential for adverse drug- drug interactions -an H2 anti-histamine
Cimetidine (Tagamet®)
82
Exhibits some CYP interference but < than cimetidine -an H2 anti-histamine
Ranitidine (Zantac®)
83
The most potent H2 anti-histamine -no CYP interference
Famotidine (Pepcid)
84
Hydrophilic; at therapeutic doses they do not enter CNS
H2 Antihistamines
85
Highly specific; do not affect H1 or H3 receptor signaling
H2 antihistamines
86
Treat uncomplicated gastroesophageal reflux disease (GERD) (aka heart burn or dyspepsia)
H2 antihistamines
87
H2 antihistamines promote healing of
Gastric and duodenal ulcers
88
Treat Zollinger-Ellison syndrome (caused by a hyper-gastrinsecreting tumor of the pancreas or duodenum)
H2 antihistamines
89
Interference with hepatic cytochrome P450 metabolic pathways (CYP1A2, CYP2C9, CYP2D6, CYP3A4); potential increased ½-life of other drugs metabolized by these pathways
H2 antihistamines Cimetdidine and Ranitidine
90
Can occur in patients with impaired renal or hepatic function using H2 antihistamines
Neurological effects

Immunity (33 decks)

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