S2 Antihistamines

Question 1

Cromoglycate

Answer 1

Cromolyn brand

Mast cell “stabilizer”

Question 2

Diphenhydramine

Answer 2

Benadryl brand
H1-receptor antagonist
First generation antihistamine

Question 3

Cimetidine

Answer 3

Tagamet brand
H2-receptor antagonist
Inhibits gastric acid secretion

Question 4

Epinephrine

Answer 4

Functional antagonist of histamine
Causes vasoconstriction
Treats systemic anaphylaxis

Question 5

Chlorpheniramine

Answer 5

Chlor-Trimeton
H1-receptor antagonist
First generation antihistamine

Question 6

Pyrilamine

Answer 6

Histavet-P brand
H1-receptor antagonist
First generation antihistamine

Question 7

Meclizine

Answer 7

Bonine brand
H1-receptor antagonist
First generation antihistamine
With Hydroxyzine

Question 8

Cetirizine

Answer 8

Zyrtec brand
H1-receptor antagonist
Second generation antihistamine

Question 9

Loratidine

Answer 9

Claritin brand
H1-receptor antagonist
Second generation antihistamine
Similar to Fexofenadine
May alleviate some types of pain

Question 10

Fexofenadine

Answer 10

Allegra brand
H1-receptor antagonist
Second generation antihistamine
Similar to Loratidine

Question 11

Hydroxyzine

Answer 11

H1-receptor antagonist
First generation antihistamine
With Meclizine

Question 12

H1 receptor locations & functions

Answer 12

1. Neurons = itching & pain
2. *Smooth muscle = +/- contraction
3. Endothelial & epithelial cells = permeability
4. Immune cells

Question 13

H2 receptor locations & functions

Answer 13

1. Neurons
2. *Parietal cells (stomach) = gastric acid secretion
3. *Heart
4. Endothelial & epithelial cells
5. Immune cells

Question 14

H3 receptor locations & functions

Answer 14

1. Neurons = pre-synaptic inhibition

2. Immune cells

Question 15

H4 receptor locations & functions

Answer 15

1. *Bone marrow
2. *Spleen = eosinophil chemotaxis
3. Immune cells = anti-inflammatory

Question 16

H1 receptor second messenger

Answer 16

Increases intracellular calcium

Question 17

H2 receptor second messenger

Answer 17

Increases cAMP

Question 18

H3 receptor second messenger

Answer 18

Decreases cAMP

Question 19

H4 receptor second messenger

Answer 19

Decreases cAMP

Question 20

Ketotifen

Answer 20

Zaditor brand
H1-receptor antagonist
First generation antihistamine
Binds receptors in the CNS = ocular use

Question 21

Acrivastine

Answer 21

Sempra brand
Alkylamine chemical class
H1-receptor antagonist
Second generation antihistamine

Question 22

Side effects of first generation H1 antihistamines

Answer 22

1. Muscarinic cholinergic effects
   a. Xerostomia (dry mouth)
   b. Urinary retention
   c. Sinus tachycardia (atropine-like)
2. Alpha-adrenergic effects
   a. Hypotension
   b. Tachycardia

Question 23

Indications for using H1 antihistamines

Answer 23

1. Allergic disease
2. Motion sickness (CNS vomiting centers)
3. Mast cell tumors