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D1 Spring > Pharmacology - Histamine and Anti-histamines (Exam 3) > Flashcards

Pharmacology - Histamine and Anti-histamines (Exam 3) Flashcards

1
Q

Chemically classified as an amine, an organic molecule based on the structure of ammonia

A

Histamine

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2
Q

Formed by the decarboxylation of the amino acid histidine

A

Histamine

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3
Q

Where are the highest levels of histamine storage?

A

Lungs
Intestinal mucosa
Skin

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4
Q

What is histamine stored in?

A

Vesicles within mast cells (mostly)

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5
Q

These cells synthesize histamine and store it within a complex w/ heparin or chondroitin sulfate in secretory granules

A

Mast cells

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6
Q

How is histamine released from secretory granules?

A

Exocytosis
Degranulation

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7
Q

Riya is allergy prone to bananas, and she makes large amounts of banana antibody and these ________ antibodies will attach themselves to ________ cells.

A

IgE; mast

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8
Q

True or False: The 1st time Riya experiences an allergic rxn to bananas is going to be much worse than the 2nd

A

FALSE, the 2nd time is much worse

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9
Q

3 major causes of histamine release

A

1) tissue injury
2) allergic rxns
3) drugs & foreign substances

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10
Q

Histamine release in response to tissue injury?

A

initial sharp phase of release (within minutes) that’s sustained over several hours

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11
Q

Initial histamine release ________ vascular permeability

A

increases

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12
Q

Antihistamines work best in the _________ phase of histamine release, rather than the sustained phase

A

initial

(once you go into anaphylaxis, it is too late for antihistamines)

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13
Q

What are some drugs that people are allergic to?

A

Morphine
Dextran
Antimalarial drugs
Antibiotics

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14
Q

Pharmacological effects of histamine on cardiovascular system

A

Vasodilation (decrease BP)
Increased permeability (edema)
Systemic hypotension

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15
Q

What is the triple effect (caused by histamine)?

A
  1. Redding @ injection site due to vasodilation
  2. Wheal or disc of edema within 1-2 mins
  3. Large bright crimson flare/halo surrounding the wheal
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16
Q

Pharmacological effects of histamine on smooth muscle of bronchioles

A

contraction of vascular smooth muscle -> difficult to breathe!

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17
Q

Histamine increases the secretion of ___________ glands

A

exocrine

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18
Q

Pharmacological effects of histamine on peripheral nervous system

A

Itching
Pain

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19
Q

How many histamine receptors are there?

A

4 receptors
H1, H2, H3, H4 (but we only care about H1 and H2)

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20
Q

What kind of receptors are histamine receptors?

A

GPCRs

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21
Q

What are H1 receptors responsible for causing?

A

Allergic conditions

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22
Q

What are H2 receptors responsible for causing?

A

Gastric acid secretions

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23
Q

Distribution of H1 receptors

A

Smooth muscle
Endothelium
CNS
Heart

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24
Q

Distribution of H2 receptors

A

Vascular smooth muscle
CNS
Heart
Neutrophils
Gastric parietal cells
Uterus

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25
Function of H1 receptors (7 things)
Bronchoconstriction Vasodilation Separation of endothelial cells Itching Pain Allergic rhinitis Motion sickness
26
Function of H2 receptors (3 things)
Gastric acid secretion Vasodilation Inhibition of IgE dependent degranulation
27
________________ competitively block the action of histamine @ the histamine receptors
histamine antagonists aka anti-histamines
28
T/F: Anti-histamines have no impact on histamine formation or release
True
29
Difference between 1st and 2nd generation H1 receptor antagonists
1st generation: crosses BBB, have sedative effects 2nd generation: significantly decreased BBB penetration, significantly decreased sedation
30
T/F: A pregnant person can take 1st generation H1 receptor antagonists
FALSE
31
The side effects of 1st generation H1 receptor antagonists are due to?
CNS depression
32
Newer 2nd generation H1-antihistamines are more selective for?
peripheral histamine receptors -> less side effects
33
Drug interactions of 1st generation H1-antihistamines
Opioids Sedatives Alcohol Analgesics
34
H1 antihistamines potentiate other _____ _________
CNS depressants
35
1st generation H1 antihistamines are well absorbed from the ____ ________
GI tract
36
1st generation H1 antihistamines are widely distributed because they can do what 2 things?
Cross BBB Placental transfer
37
Oldest and most effective antihistamine on the market
Diphenyhydramine (benadryl)
38
What effects does diphenhydramine (benadryl) have?
Sedative effects
39
What is the active ingredient in Tylenol PM and dramamine?
diphenhydramine (benadryl)
40
What is the mechanism of diphenhydramine (benadryl)?
Inhibits histamine binding to H1 receptors Inhibits reuptake of serotonin
41
This is the active ingredient in NyQuil and has potent anti-cholinergic effects
doxylamine succinate
42
Dimenhydrinate (dramamine) is a combo of?
Diphenhydramine (benadryl) + 8-chlorotheophillinate (similar to caffeine)
43
What drug is used to treat motion sickness by acting on H1 receptors?
Diphenhydramine (benadryl)
44
This drug has been shown to have antidepressant properties and inhibit the reuptake of serotonin
Chlorphenamine
45
What drug is used for the antihistamine component of Visine-A?
Pheniramine
46
Used to treat motion sickness, vertigo, nausea and vomiting
Piperazines
47
Used to treat motion sickness, vertigo, and post-op following administration of general anesthesia and opiods
Cyclizine
48
Structurally related to the ethylenediamines and the ethanolamines and thus produce significant anti-cholinergic effects
Piperazines
49
Used to treat nausea, vomiting, and vertigo; causes drowsiness
Meclizine
50
This drug treats indoor and outdoor allergies and is safe to use in children as young as 2; considered a second generation drug
Cetirizine (zyrtec)
51
This drug has extremely strong anticholinergic and sedative effects; also used as anti-nausea drug for morning sickness
Promethazine
52
This drug is both an antihistamine & antiserotonergic agent; used to treat hay fever and stimulate appetite in people with anorexia
Cyprohepatidine
53
This drug has severe side effects including drowsiness, weight gain, dry mouth, irritability, and nosebleeds
Ketotifen (Zaditor)
54
Characteristics of 2nd generation H1 receptor antagonists
Bulky Less lipophilic Don't cross BBB as readily
55
These H1 antagonists are more selective for peripheral H1 receptors than CNS H1 receptors
2nd generation H1 antagonists
56
This drug does not cross the BBB and has severe interactions with erythromycin and grapefruit juice
Astemizole (Hismantol)
57
This drug has long lasting effects and does not cause drowsiness because it does not cross the BBB
Loratadine (claritin)
58
Newer H1 antagonists are either the active ________ or _______ of a ____ generation drug
enantiomer; metabolite; 2nd
59
This drug is the active enantiomer of Cetirizine and is not metabolized
Levocetirizine (Zyzal)
60
This drug is an alternative to Terfenadine
Fexofenadine (allegra) - newer 2nd gen H1 receptor antagonist
61
Name 2 H2 receptor antagonists
Cimetidine (Tagamet) Famotidine (pepcid)
62
Histamine binds to H2 receptors in the _______
Stomach
63
Clinical uses of H2 receptor antagonists
Zollinger-ellison syndrome Acid reflux
64
Adverse effects of this H2 receptor antagonist are severe CNS effects in elderly people
Cimetidine
65
All H2 antagonists, except for Famotidine (pepcid), increase the bioavailability of _______________
ethanol
66
Agents that inhibit gastric secretion alter? (2 things)
1) bioavailability 2) rate of absorption of drugs

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