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HISTAMINE AND CORTICOSTEROIDS Flashcards

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1
Q

Histamine

A
  1. Chemical messenger mostly generated in mast cells
  2. Mediates a wide range of cellular responses
    ○ Allergic and inflammatory reactions
    ○ Gastric secretion
    ○ Neurotransmission in parts of the brain
  3. One of the earliest mediator released during allergies and
    anaphylaxis
  4. Involved in Type 1 Hypersensitivity
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2
Q

Present in practically all tissue

A

Histamine

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3
Q

Histamine is found in significant amount in

A

Lungs, skin, blood vessels and
GI tract

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4
Q

Massive histamine release

A

Anaphylaxis

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5
Q

Histamine is found at high concentration in

A

Mast cells and basophils

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6
Q

Function of histamine in brain

A

Neurotransmitter

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7
Q

Formed by the __________ of the amino acid _________
by the enzyme _________ _____________

A

decarboxylation, histidine, histidine decarboxylase

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8
Q

Histamine precursor

A

Histidine

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9
Q

Decarboxylation of histamine

A

Decarboxylation→ liberate the carbon dioxide→
amine group will remain

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10
Q

Histamine binds to what type of receptors

A

H1, H2, H3, H4

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11
Q

Widely expressed and clinically relevant

A

H1 and H2

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12
Q

Histamine promotes ___________ by causing vascular endothelium to release ______ _______

A

Vasodilation, nitric oxide

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13
Q

Vasodilation caused by NO results to

A
  1. Increase in blood vessel caliber →
    laminar flow→ decreased in pressure (blood
    pressure)
  2. Promotes severe vasodilation capable of
    producing shock
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14
Q

Histamine enhance the secretion of

A

Pro-inflammatory cytokines

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15
Q

Pro-inflammatory cytokines

A

IL1, IL5, IL6, IL8, TNF

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16
Q

Histamine is stored in

A

Mast cells and basophils

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17
Q

Immunologic Release:
If sensitized by ___ ________ attached to their surface membranes, ____ _____ and _________ __________ explosively when exposed to the appropriate antigen

A

IgE antibodies, mast cells and basophils degranulate

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18
Q

Amines that competitively inhibit histamine by displacing it from its bound form

A

Morphine and tubocurarines

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19
Q

Receptor in smooth muscle

A

H1

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20
Q

Receptor in gastric mucosa

A

H2

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21
Q

Receptors found both in the brain

A

H1 and H2

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22
Q

Receptors with CNS role and plexuses

A

H3 and H4

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23
Q

H1 post receptor mechanism

A

H1→ IP3, DAG

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24
Q

H1 distribution

A

Smooth muscle, endothelium, brain

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25
H1 partially selective agonist
Histaprodifen
26
H1 partially selective antagonists or inverse agonists
Mepyramine, triprolidine, cetirizie
27
H2 distribution
Gastric mucosa, cardiac muscle, mast cells, brain
28
H2 partially selective agonist
Amthamine
29
H2 partially selective antagonists or inverse agonists
Cimetidine, ranitidine, tiotidine
30
H3 distribution
presynaptic autoreceptors and heteroreceptors; brain, myenteric plexus, other neurons
31
H3 partially selective agonist
R-a-methylhistamine, imetit, immepip
32
H3 partially selective antagonists or inverse agonists
Thioperamide, iodophenpropit, clobenpropit, tioptrolisant, proxyfan
33
H4 distribution
Eosinophils, neutrophils, CD4 T cells
34
H4 partially selective agonist
Clobenpropit, imetit, clozapine
35
H4 partially selective antagonists or inverse agonists
Thioperamide
36
H1 actions
Exocrine secretion, Bronchial Smooth Muscle, Intestinal Smooth Muscle, Sensory Nerve Endings
37
Exocrine Secretion
Increased production of nasal and bronchial mucus, resulting in respiratory symptoms
38
Bronchial Smooth Muscle
Constriction of bronchioles results in symptoms of asthma and decreased lung capacity
39
Intestinal Smooth Muscle
Constriction results in intestinal cramps and diarrhea
40
Sensory Nerve Endings
Causes itching and pain
41
H1 and H2 actions in
CVS and skin
42
CVS action of H1 and H2
1. Reduced peripheral resistance = low systemic BP 2. (+) chronotropism (heart rate; H2-mediated) 3. (-) inotropism (myocardial contractility)
43
Skin action of H1 and H2
1. Dilation and increased permeability of the capillaries ○ Results in leakage of proteins and fluid into the tissues ○ Transcellular shift from intravascular to the interstitial→ edema 2. Results in Triple Response ○ Wheal formation ○ Reddening due to local vasodilation ○ Flare (Halo)
44
Stomach action of H2
Stimulation of gastric hydrochloric acid secretion
45
Have smooth muscle actions opposite to those of histamine → act at different receptors
Antihistamines (physiologic antagonist)
46
Epinephrine
■ Promotes vasoconstriction ■ Stimulation of α1 → α1 is for vasoconstriction ■ Inhibition of α2 → α2 is for vasodilation ■ Stimulates β1 → ↑ heart rate ■ Stimulates β2 → promoting bronchodilation ■ Stimulates β3 → promoting glycolysis ■ For anaphylaxis
47
Release inhibitors
Reduce the degranulation of mast cells
48
Examples of release inhibitors
Cromolyn and Nedocromil
49
Cromolyn and Nedocromil
■ For cough and asthma ■ Mast cells stabilizers→ control release of histamine
50
Receptor antagonist
Reduction of histamine-mediated responses
51
H1-Receptor Antagonists
● Competitively block the histamine or act as inverse agonists at H1 receptors ○ Prevention of vasodilation and other inflammatory reactions
52
H1-Receptor Antagonists actions
● Sedation ● Antinausea and antiemetic actions ● Antiparkinsonism effects ● Antimuscarinic actions ● Adrenoreceptor-blocking actions ● Serotonin-blocking actions ● Local anesthesia ○ First-generation H1 antagonists are potent local anesthetics
53
Sedation
○ Common effect of first-generation H1-antagonists ○ Benadryl ■ Antihistamine with sedating effect
54
Antinausea and antiemetic drug
Doxylamine
55
Antiparkinsonism drug
Diphenhydramine
56
Antimuscarinic
Ethanolamine and Ethylenediamine subgroup
57
Adrenoreceptor-blocker
Promethazine
58
Serotonin-blocker
Cyproheptadine
59
Anticholinergic activity
● Controls secretion ● Anti GI and GU
60
Diphenhydramine
● Promote dry mouth and constipation ● Anti-motion sickness activity ● Marked sedation ○ Groggy
61
Alkylamines
● Brompheniramine ○ Dimetapp (dropper for kids) ● Chlorpheniramine ○ Slight sedating effect ○ Over-the-counter cold medication ○ Generic name of Bioflu ■ Phenylephrine + chlorphenamine maleate
62
Phenothiazine derivative
Promethazine
63
Hydroxyzine
● Atarax ● Not available in the market ● Anti-allergy that is stronger than Cetirizine but not as strong as Diphenhydramine ● Levocetirizine → Cetirizine → Hydroxyzine → Diphenhydramine ● The older the generation of antihistamine the greater the sedative effect
64
Second generation antihistamines have some ____ sedating
mild
65
2nd gen antihistamine that is the safest, minimal sedating, longer action
Loratadine
66
Often the first drug used to prevent or treat the symptoms of allergic reactions
H1 antihistaminic agents
67
Used mainly for the treatment of allergic rhinitis and chronic urticaria
Second-generation H1 antagonists
68
Motion Sickness and Vestibular Disturbances: Most effective agents available for the prevention of motion sickness
Scopolamine and certain first-generation H1 antagonists
69
Drugs for Nausea and Vomiting of Pregnancy
Doxylamine, an ethanolamine H1 antagonist
70
1st gen drugs with marked potential for producing sedation
Brompheniramine Chlorpheniramine Clemastine Cyproheptadine Diphenhydramine Doxylamine Hydroxyzine Promethazine
71
1st gen drugs used to treat motion sickness
Cyclizine Diphenhydramine Dimenhydrinate Hydroxyzine Meclizine Promethazine
72
2nd gen drugs with weak potential for producing sedation
Cetirizine Lovecetirizine
73
Non-sedating 2nd gen drugs
Desloratadine Loratadine Fexofenadine
74
Promethazine prevents ____-_______ receptors thereby producing _______, ________, and ______ ________
alpha-adrenergic hypotension, dizziness, and reflex tachycardia
75
If anticholinergic receptors are prevented, it will produce
Dry mouth, urinary retention, and sinus tachycardia
76
Anti-serotonin that increases appetite
Cyproheptadine
77
Their chief clinical use is as inhibitors of gastric acid secretion in the treatment of ulcers and heartburn
H2-Receptor Antagonists
78
The four H2 receptor blockers
Cimetidine Ranitidine Famotidine Nizatidine
79
Cimetidine
■ No longer widely used ■ Promotes gynecomastia and hirsutism ■ Promotes drug-to-drug interactions in CYP liver enzymes
80
Ranitidine
Most commercially available
81
Famotidine
Longest acting and most potent
82
H3-selective ligands may be of value
Sleep disorders, narcolepsy, obesity, and cognitive and psychiatric disorders
83
An inverse H3-receptor agonist shown to reduce sleep cycles in mutant mice and in humans with narcolepsy
Tiprolisant
84
Side effect of H1 and H3 receptor in mice
Increased obesity
85
H1 receptor affects serotonergic pathway →
↑ appetite → obesity
85
Have potential in chronic inflammatory conditions, such as asthma in which eosinophils and mast cells play a prominent role
H4-receptor Blockers

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