Antihistamines and Related Antiallergic Agents

Question 1

Where does histamine synthesis occur?

Answer 1

in many tissues, including mast cells, parietal cells of the gastric mucosa, and neurons of the central nervous system (CNS) and in the periphery

Question 2

Histamine gives a ___________ effect

Answer 2

local

Question 3

What is used in the treatment of allergic inflammatory disorders?

Answer 3

H1 antihistamines

Question 4

What is used in the treatment of gastric hypersecretory disorders?

Answer 4

H2 antihistamines

Question 5

Histamine plays a physiologic role at several regions of the CNS via which receptors?

Answer 5

H3 and H4

Question 6

The stimuli for release of histamine from tissues may include?

Answer 6

• destruction of cells as a result of cold
• allergies and anaphylaxis
• toxins from organisms
• venoms from insects and spiders
• trauma

Question 7

Why are histamines released by injured tissues?

Answer 7

to recruit white blood cells at the site of injury by inducing vasodilation

Question 8

What is the effect of H1 receptors on smooth muscle?

Answer 8

relaxation

Question 9

What is the effect of H1 receptors on capillary permeability?

Answer 9

increases capillary permeability

Question 10

How does histamine promote vasodilation of small blood vessels?

Answer 10

by causing the vascular endothelium to release nitric oxide

Question 11

Effect of H1 receptors on bronchioles?

Answer 11

constriction

Question 12

Which histamine receptors mediate many pathological processes, including allergic rhinitis, atopic dermatitis, conjunctivitis, urticarial, bronchoconstriction, asthma, and anaphylaxis?

Answer 12

H1

Question 13

What is the main difference between first and second generation H1 antihistamines?

Answer 13

selectivity and side effects

Question 14

________________ are useful in the treatment of allergy and inflammatory disorders

Answer 14

H1 antagonists

Question 15

First-generation H1 antihistamines are effective in the treatment of?

Answer 15

allergic responses (e.g., hay fever, rhinitis, urticaria, and food allergy)

Question 16

Adverse central effects of first-generation antihistamines include?

Answer 16

sedation, drowsiness, decreased cognitive ability,

and somnolence

Question 17

Peripheral side effects associated with cholinergic blockade include?

Answer 17

blurred vision, dry mouth, urinary retention, and constipation

Question 18

Second-generation H1 antihistamines give what effects?

Answer 18

separation of CNS depressant and anticholinergic effects from peripheral antihistaminic effects

Question 19

Are first-generation H1 antihistamines selective?

Answer 19

no

Question 20

Are second-generation H1 antihistamines selective?

Answer 20

yes

Question 21

Advantages of second-generation H1 antihistamines?

Answer 21

• more selective for H1 receptor

- less CNS effects

Question 22

Disadvantages of first-generation H1 antihistamines?

Answer 22

• nonselective which leads to many side effects

- can reach CNS and cause sedation

Question 23

What happens when H1 antihistamines inhibit cholinergic receptors?

Answer 23

• dry mouth
• urinary retention
• sinus tachycardia

Question 24

What happens when H1 antihistamines inhibit a-Adrenergic receptors?

Answer 24

• hypotension
• dizziness
• reflex tachycardia

Question 25

What happens when H1 antihistamines inhibit serotonin receptors?

Answer 25

increased appetite

Question 26

What happens when H1 antihistamines inhibit histamine H1 receptors?

Answer 26

- lowered allergic inflammation, itching, sneezing, and rhinorrhea - lowered neurotransmission in the CNS - sedation - lowered cognitive and psychomotor performance - increased appetite

Question 27

Most H1 antihistamines are?

Answer 27

inverse agonists

Question 28

What does the structural scaffold of H1 antagonists (first generation antihistamines) include?

Answer 28

- tertiary amine - spacer - 2 aromatic or heteroaromatic rings

Question 29

What is the difference between H1 and H2?

Answer 29

H2 usually has an imidazole but H1 antagonist has only aromatic or heteroaromatic rings

Question 30

What are the oldest first-generation antihistamine that are not widely used anymore?

Answer 30

ethylenediamines

Question 31

Do ethylenediamines cause CNS effects mainly sedation?

Answer 31

yes

Question 32

The prototype of the aminoalkyl ethers is?

Answer 32

diphenhydramine

Question 33

Do ethanolamine ethers cause significant anticholinergic side effects and sedation?

Answer 33

yes

Question 34

What type of antihistamines is used as OTC sleep aids?

Answer 34

ethanolamine ethers

Question 35

Compounds with central anticholinergic and antihistaminic effects have been used as one approach to the treatment of?

Answer 35

Parkinson disease

Question 36

__________ are widely used OTC antihistamines for mild seasonal allergies.

Answer 36

alkyl amines

Question 37

Compared to the ethylenediamines and ethanolamine ether series, alkyl amines are characterized by a _________ duration for antihistaminic action and a ________ incidence of central sedative side effects

Answer 37

long; decreased

Question 38

Do piperazines give anticholinergic side effects and drowsiness?

Answer 38

yes

Question 39

What is the primary use of piperazines?

Answer 39

treatment of motion sickness and vertigo and for suppression of nausea and vomiting

Question 40

What is the effect of most tricyclic H1 antihistamines?

Answer 40

sedative effects and long durations of action

Question 41

Do second-generation H1 antihistamines penetrate the blood-brain barrier?

Answer 41

no because of their amphoteric nature or they are substrates for transporter proteins

Question 42

Name the second-generation H1 antihistamines with weak potential for producing sedation

Answer 42

1. acrivastine 2. cetririzine 3. levocetirizine

Question 43

Name the second-generation H1 antihistamines that are nonsedating

Answer 43

- desloratadine - fexofenadine - loratadine