Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Respiratory Block: Pharmacology > Antihistamines > Flashcards

Antihistamines Flashcards

1
Q

Pharmacological effects of Histamine: Which receptors are found in the Nervous System and what is the effect of their simulation?

A

H1 - pain and itching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Pharmacological effects of Histamine: Which receptors are found in the Cardiovascular System and what is the effect of their simulation?

A

H1 & H2 - decreased BP, increased HR

H2 - increased contractility, increased pacemaker rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Pharmacological effects of Histamine: Which receptors are found in the Bronchial smooth muscle and what is the effect of their simulation?

A

H1 - bronchoconstriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Pharmacological effects of Histamine: Which receptors are found in the GIT smooth muscle and what is the effect of their simulation?

A

H1 - contraction, diarrhea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Pharmacological effects of Histamine: Which receptors are found in the Secretory tissue (stomach) and what is the effect of their simulation?

A

H2 - increased gastric acid secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Pharmacological effects of Histamine: Which receptors are found in the Triple response (capillaries) and what is the effect of their simulation?

A

H1 +++++, H2
= Wheal & flare response, 3 cell types involved:
1. Smooth muscle in microcirculation
2. Capillary and venular endothelium
3. Sensory nerve endings
= increased dilation of small vessels, increased permeability, edema and itch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Pharmacological effects of Histamine: Which receptors are found in the Exocrine Secretion and what is the effect of their simulation?

A

H1 & H2 - Production of nasal and bronchial mucous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Pharmacological effects of Histamine: Which receptors are found in the Central Nervous System and what is the effect of their simulation?

A

H1 - Excitation (arousal, wakefulness) + control of food and water intake
H2 + H3 - Inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Antihistamines are divided into what groups?

A

1st, 2nd, and 3rd generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the characteristics of the 1st generation?

A

Strong sedative effects, block autonomic receptors.

enter CNS readily

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the characteristics of the 2nd generation?

A

Less sedation and less complete distribution into the CNS , some are cardiotoxic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the characteristics of the 3rd generation?

A

Non-sedative and Non-cardiotoxic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pharmacokinetics: How rapidly are the drugs absorbed?

A

Rapidly absorbed after oral administration

- peak blood concentration after 1-2 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Pharmacokinetics: How are several of the second generation antihistamines metabolized?

A

By the enzyme CYP3A4 which can lead to drug interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Pharmacokinetics: What is the duration of action?

A

Between 4-6 hours

- but Meclizine and several 2nd generation antihistamines have longer duration of action: 12-24 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pharmacokinetics: What is the lipid solubility?

A

Newer generations are less lipid soluble than the older generations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the active metabolite of Hydroxyzine?

A

Cetirizine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the active metabolite of Terfenadine?

A

Fexofenadine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the active metabolite of Loratadine?

A

Desloratadine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the mechanism of action of the antihistamines?

A

Block the action of histamine by reversible competitive antagonism at H1-receptors, little effect on H2 or H3 receptors.

  • Histamine-induced contraction of bronchial or GIT smooth muscle is completely blocked
  • Effect on gastric acid secretion & heart are unmodified
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Other effects of antihistamines (only 1st generation) not caused by H-1 receptor blockage on the CNS (H1)

A
  • Sedation, some useful as sleep acids
  • May cause excitation in children
  • Toxic doses = stimulation, agitation, convulsions, coma
22
Q

Other effects of antihistamines (only 1st generation) not caused by H-1 receptor blockage on the muscarinic cholinergic-receptor block

A
  • Prevents motion sickness, decreased effectiveness when motion sickness is already present
  • anti-vertigo
  • anti-Parkinsonism
  • decreased secretions (peripheral)
23
Q

Other effects of antihistamines (only 1st generation) not caused by H-1 receptor blockage on alpha-adrenoreceptor block

A

Hypotension (promethazine)

24
Q

Other effects of antihistamines (only 1st generation) not caused by H-1 receptor blockage on serotonin receptor block

A
  • appetite stimulation / weight gain

Cyproheptadine

25
Other effects of antihistamines (only 1st generation) not caused by H-1 receptor blockage on Na channel block
Local anesthesia
26
Other effects of antihistamines (only 1st generation) not caused by H-1 receptor blockage: which drug inhibits mast cell release of histamine?
Cetirizine (active metabolite of hydroxyzine)
27
Which antihistamines should be used for allergic reactions?
More the second and third generation antihistamines
28
Which antihistamines should be used for allergic rhinitis
1. Systemic antihistamines - mild cases with / without systemic nasal decongestants (pseudoephedrine), 2nd, 3rd generation less sedation 2. Topical preparations = LEVOCABASTINE, AZELASTIN - seasonal allergic rhinitis
29
What is Azelastine used for?
Topical preparation antihistamine - allergic rhinitis - blocks H-1 receptors - inhibits the release of inflammatory mediators from mast cells
30
What is Levocabastine used for?
Topical preparation antihistamine - long acting - short-term symptomatic treatment of seasonal allergic rhinitis
31
Which antihistamines should be used for atopic dermatitis?
Diphenhydramine | - 1st generation, sedative and itching effects
32
Which antihistamines should be used for Hay fever?
Alkylamines and second generation | - want to minimize sedation
33
In anaphylaxis, antihistamines are a secondary treatment to what?
Adrenaline
34
Which antihistamines should be used as antiemetics (nausea and vomiting)?
1. Doxylamine* 2. Cyclizine* 3. Buclizine
35
Which antihistamines should be used for motion sickness and vestibular disturbances (vertigo)?
``` 1st Generation for prevention of motion sickness: 1. Diphenhydramine 2. Promethazine 3. Cyclizine (& Meclizine) ```
36
What drugs should be used with antihistamines for more effective control of motion sickness and vestibular disturbances (vertigo)?
Ephedrine or amphetamine
37
Which antihistamines should be used for postoperative medication?
Promethazine | - sedation, antimuscarinic & antiemetic
38
Which antihistamines should be used for sedation?
1. Diphenhydramine* 2. Doxylamine = induces sleep, may not however maintain sleep
39
Which antihistamines should be used as an antipruritic?
Diphenyhydramine | - reduces itching
40
Which antihistamines should be used as an appetite stimulant?
Cyproheptadine
41
Which antihistamines should be used for rhinorrhea in colds and flu?
This is primarily the antimuscarinic activity of the 1st generation antihistamines = drying of secretions, specifically nasal secretions (also cause dry mouth due to the same effect)
42
How are antihistamines used for rhinorrhea in colds and flu usually found?
In polycomponent cold and flu preparations as they: - increase tenacity of secretions - interfere with normal ciliary function - cause drowsiness
43
Which antihistamine is the antidote to "serotonin syndrome"?
Cyproheptadine
44
Which antihistamines should be used for anti-Parkinsonism?
1. Promethazine | 2. Dophenhydramine
45
Which antihistamines should be used as antitussives?
Peripherally acting antihistamines (1st generation) - block cholinergic nerve impulses = dry up secretions = mucous plug formation - PROMETHAZINE + DIPHENHYDRAMINE
46
When should antihistamines not be used as antitussives?
Not for productive coughs or asthmatics
47
Antihistamines as antitussives: Promethazine
Causes sedation
48
Antihistamines as antitussives: Chlorpheniramine
Causes less sedation than promethazine, however still causes sedation
49
Antihistamines as antitussives: Diphenhydramine
Potent antitussive and sedative
50
Antihistamines as antitussives: Mepyramine maleate
Less sedating
51
Antihistamines as antitussives: Tripolidine
Acts for up to 12 hours
52
Which antihistamines should be used for local anaesthesia?
1. Diphenhydramine 2. Promethazine - when patients are allergic to the usual anaesthetics

Respiratory Block: Pharmacology (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions