Histamine and Antihistamine Flashcards Preview

D&T 3 test 2 > Histamine and Antihistamine > Flashcards

Flashcards in Histamine and Antihistamine Deck (62):
1

what is histamine synthesized from? what enzyme is used

histidine
- histidine decarboxylase (HDC)

2

Where is histamine predominately synthesized and stored

MAST CELLS

3

Where is histamine synthesize/stored in non-mast cell sites

1. gastric enterochromaffin-like (ECL) cells
2. epidermis
3. CNS neurons

4

what does histamine get metabolized into

1. N-methylhistamine
2. imidazole acetic acid

5

what converts N-methylhistamine into N-methylimidazoleacetic acid

monoamine oxidase (MAO)

6

When is histamine released

sensitized cells in response to allergen

7

what are other substances that release histamine from mast cells

CURARE
MORPHINE
venoms
inflammatory mediators

8

what releases histamine from gastric ECL cells

ACETYLCHOLINE (Ach) AND GASTRIN

9

How does histamine work in the CNS

acts as a neurotransmitter

10

Where is H1 receptors usually found

smooth muscle
endothelium
brain

11

Where is H2 receptor usually found

gastric mucosa
cardiac muscles
mast cells
brain

12

what are post-receptor mechanism for H1

Gq
IP3
increase DAG

13

What is a partially selective antagonist for H2 receptor

Ranitidine

14

what is a partially selective agonist for H1 receptor

2-CH3-histamine

15

what is the post-receptor mechanism for H2 receptor

Gs
increase cAMP

16

what is the partial selective agonist for H2 receptor

Dimaprit

17

what is the partially selective antagonist for H1 receptor

Chlorpheniramine

18

What receptor is located in blood vessels

H1 receptor

19

how does histamine directly impact blood vessels

- Vasodilation
- decrease TPR, BP
- flushing

20

how does histamine indirectly impact blood vessels

- release of endothelium-derived NO (nitric oxide) and PGI2 (rapid and short lived)

21

what histamine receptor is found in the capillaries

H1

22

how does histamine impact capillary permeability? impact?

increases permeability
causes edema

23

what histamine receptor works on the lungs

H1

24

histamine impact on lungs

bronchoconstriction ( especially asthmatics)

25

what histamine receptor works on gastric mucosa

H2

26

histamine impact of gastric mucosa

increase acid secretion from parietal cells

27

what receptor works on cutaneous sensory nerve endings

H1

28

histamine impact on cutaneous sensory nerve endings

Pruritus ( epidermis)
pain and itching ( dermis)

29

what receptor works in brain

H1

30

what are histamine effects in CNS

Neurotransmitter
- increases wakefulness and inhibits appetite

31

what receptor is involved in the triple response

H1

32

what is the triple response

1. red spot - vasodilation
2. Wheal - increase capillary premeability
3. Flare - axon reflex, vasodilation

33

Name a physiological antagonist? when is it used?

epinephrine
- systemic anaphylaxis

34

how do histamine release inhibitors work?

antigen-IgE interaction

35

how do histamine receptor antagonists work

competitively antagonize on smooth muscle cells

36

how do H1 receptor antagonists work

reversible competitive antagonist specifically at H1 receptors

37

Name the 1 st generation histamine antogonists

Chlorpheniramine
Diphenhydramine
Hydroxyzine
Promethazine

38

Name the second generation histamine antagonist

Cetirizine
Loratadine
Fexofenadine

39

which first generation histamine antagonist has the greatest CNS sedation and antimuscarinic activity

Promethazine

40

first generation H1 receptor histamine antagonist enter what part of the body rapidly

CNS

41

who metabolizes Loratadine

Cyp3A4

42

How does H1 receptor antagonist impact vasodilation?

inhibits it

43

How does H1 receptor antagonist impact permeability

strongly blocks

44

How does H1 receptor antagonist impact increased heart rate

partially block

45

How does H1 receptor antagonist impact bronchoconstriction

reduced a little

46

How does H1 receptor antagonist impact acid secretion

do not suppress

47

How does H1 receptor antagonist impact pruritus

some relief

48

How does H1 receptor antagonist impact flare and itching

suppresses both

49

what is the antimuscarinic effect of H1 antagonists

inhibit responses to acetylcholine that are mediated by muscarinic receptors

50

which H1 antagonists have anti-muscarinic effects

- Promethazine strongest
- second generation have no effect

51

which H1 antagonists are best at combating motion sickness

Promethazine

52

what are 4 major adverse effects of H1 antagonist and class causes each ADR

1. CNS stimulation
2. CNS depression - 1 generation and Cetirizine
3. antimuscarinic effects - 1st generation
4. GI - 1st generation

53

CNS depression from 1 st generation and Cetirizine is potentiated by what

alcohol and CNS depressants

54

what is the pharmacokinetics for 2nd generation

poorly distributed to CNS

55

what are 4 main therapeutic uses for histamine antagnoists

- treat acute exudative allergy (hay fever, rhinitis)
- bronhcial asthma ( not sole therapy)
- systemic anaphylaxis ( epinephrine)
- motion sickness and induce sedation ( 1st generation)

56

Name 3 H2 receptor antagonists

Cimetidine
Ranitidine
Famotidine

57

how do H2 antagonists work

competitive antagonist at H2 receptor

58

what are the effects of H2 antagonists

decrease gastric acid secretion

59

what are adverse effects of H2 antagonists

Headache
GI
Fatigue, drowsiness

60

how is H2 antagonists excreted

renal- reduce dose in renal disease

61

what are drug interactions for H2 antagonists

Cimetidine inhibits cytochrome P450

62

what is a therapeutic use for H2 antagonist

1. promote healing of peptic ulcer and duodenal ulcer
2. uncomplicated GERD
3. prophylaxis of stress ulcer