Smooth Muscle Allergy and Pulmonary Drugs: Antihistamines

Question 1

histamine is located in

Answer 1

histamine sequestered inside the granules of mast cells

Question 2

H1 histamine receptor is coupled to

Answer 2

H1 histamine receptor is coupled to Gq protein (mediates allergic inflammation)

Question 3

H2 histamine receptor is coupled to

Answer 3

Gs protein

Question 4

H2 histamine receptor mediates

Answer 4

gastric acid secretion

Question 5

histamine H1 receptor activation increases

Answer 5

1. nasal and bronchial mucus production

2. vascular permeability

Question 6

histamine H1 receptor activation causes

Answer 6

constriction of bronchial smooth muscle

Question 7

histamine functions as a

Answer 7

neurotransmitter (H1 receptor regulates sleep and arousal)

Question 8

H1 receptor blocker (antihistamine) treats

Answer 8

allergy

Question 9

1st-generation H1 receptor blockers

Answer 9

1. diphenhydramine
2. dimenhydrinate
3. chlorpheniramine
4. hydroxyzine
5. meclizine
6. promethazine

Question 10

histamine mediates type-1 allergic reaction

Answer 10

histamine mediates type-1 allergic reaction → hives, allergic rhinitis (H1 receptor blockers are first line therapy)

Question 11

1st-generation H1-blockers treat

Answer 11

1st-generation H1-blockers treat vestibular nausea or motion sickness (lipophilic → enter CNS → act on vestibular system and brainstem)

Question 12

1st-generation H1-blockers cause

Answer 12

1st-generation H1-blockers cause drowsiness (lipophilic → cross BBB → central effects)

Question 13

1st-generation H1-blockers antagonize

Answer 13

1. peripheral and central muscarinic receptors
2. serotonin receptors in the CNS
3. alpha 1 receptors

Question 14

1st-generation H1-blockers treat

Answer 14

1st-generation H1-blockers treat extrapyramidal side effects caused by antipsychotics, e.g. acute dystonia (antimuscarinic effects re-establish dopaminergic-cholinergic balance)

Question 15

1st-generation H1-blockers antagonize peripheral and central muscarinic receptors causing

Answer 15

1st-generation H1-blockers antagonize peripheral and central muscarinic receptors (e.g. pupillary dilation, dry mouth, urinary retention, constipation, exacerbation of glaucoma, and delirium)

Question 16

1st-generation H1-blockers stimulate

Answer 16

appetite and weight gain (anti- serotonergic effects)

Question 17

1st-generation H1-blockers antagonize alpha-1 receptors

Answer 17

1st-generation H1-blockers antagonize alpha-1 receptors → dizziness and hypotension

Question 18

1st-generation H1-blockers cause

Answer 18

1. dizziness and hypotension (anti alpha- adrenergic effects)
2. cognitive impairment in the elderly (central antihistamine and antimuscarinic effects)

Question 19

2nd-generation H1-blockers

Answer 19

1. fexofenadine
2. cetirizine
3. loratidine

Question 20

2nd-generation H1-blockers

Answer 20

2nd-generation H1-blockers are less lipophilic → do not cross BBB → less sedating (also less antimuscarinic, antiserotonergic, or anti-alpha adrenergic properties)