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Pharm > Anti-histamines > Flashcards

Anti-histamines Flashcards

1
Q

What are autacoids?

A

biological factors which act like local hormones, have a brief duration, and act near the site of synthesis. The word autacoids comes from the Greek “Autos” (self) and “Acos” (relief, i.e. drug).

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2
Q

What is the triple response of Lewis?

A
  • Red spot (capillary dilation)
  • Flare (stimulate nerve to dilate)
  • Wheal (increased capillary permeability)
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3
Q

What is histamine (what is it made from, and how is it different)?

A

Histidine without its carboxyl group

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4
Q

What is the enzyme that converts histidine to histamine?

A

Histidine decarboxylase

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5
Q

What is the use of histamine?

A

Plays a central role in immediate hypersensitivity reaction

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6
Q

What happens to histamine when it is released into tissues and blood?

A

Inactivated

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7
Q

What are the cells that contain histamine? (3)

A
  • Mast cells
  • Basophils
  • Enterochromaffin-like cells
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8
Q

Where are mast cells found in high concentrations?

A

Bronchial and intestinal mucosa

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9
Q

Histamine release causes the release of what cytokines?

A

Leukotrienes
Cytokines
Enzymes

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10
Q

What are the two MOAs of histamine release?

A

Cytolytic

Noncytolytic

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11
Q

What is the cytolytic histamine release pathway?

A

Membrane damage leads to high levels of histamine release

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12
Q

What cause cytolytic release of histamine?

A

High levels of drugs such as phenothiazine, H1 receptor antagonists, opioids

Mechanical damage

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13
Q

What is the noncytolytic mechanism of histamine release?

A

Immune response that requires prior sensitization, leading to displacement of histamine

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14
Q

What is the MOA of allergic reaction and histamine release?

A

Antigen binds in Ig ab (FC-epsilon-R1) receptor on plasma cells, that then produces IgE that integrate into mast cells.

The next time they stimulate mast cells directly throught IgE

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15
Q

What are the three major chemicals that are released during anaphylaxis, besides histamine?

A

Leukotrienes
Prostaglandins
Cytokines

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16
Q

What is anaphylactoid?

A

Clinical syndrome indistinguishable from anaphylaxis, but not caused by an immune response

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17
Q

Where is H1 receptor highly expressed (3)? What G protein?

A

Smooth muscle
Vascular endothelial cells
CNS neurons

Gq

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18
Q

Where is H2 receptor highly expressed (3)? What G protein?

A

Gastric parietal cells
Cardiac muscle
CNS neurons

Gs

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19
Q

Where is H3 receptor highly expressed (2)? What G protein?

A

CNS neurons
Peripheral sensory nerves

Gi/o

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20
Q

Where is H4 receptor highly expressed (3)? What G protein?

A

PMNs
Eosinophils
Monocytes

Gi/o

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21
Q

Where in the brain is there a large amount of histamine receptors?

A

Hypothalamus

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22
Q

What is the cyclical pattern of histamine levels? What is the function of this?

A

High in the day
Low at night

Functions in sleep and appetite

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23
Q

What is the transmitter that mediates itch? Where does this act?

A

H1 receptors in the periphery

Centrally and peripherally

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24
Q

What happens when H1 is activated in vessels?

A

NO released from PKC activation, causing vasodilation

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25
Q

What happens when H2 is activated in vessels?

A

PKA causes vasodilation

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26
Q

What is the main receptor that mediates increased permeability of endothelial cells?

A

H1

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27
Q

H1 activation in the epidermis causes what? Dermis?

A 
Epidermis = itch
Dermis = pain
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28
Q

What histamine receptor increases airway fluid secretion?

A

H1

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29
Q

What type of histamine receptor is on the heart? Effect?

A 
H2
Increased Ca (force and nodal speed)
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30
Q

Which response is greater: H1 vasodilation reflex tachycardia, or H2 receptor activation increase in HR?

A

H1

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31
Q

How does histamine help with immune system function?

A

Facilitate the accumulation of immune cells at the site of damage (p-selectins, integrins, and adhesions)

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32
Q

What WBC finding is found in CML? What is the significance of this?

A

Basophilia–can cause itching from histamine release

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33
Q

Gastric carcinoid tumors that secrete histamine cause what?

A

Episodes of vasodilation

34
Q

What is mast cell leukemia? Ssx?

A

Mast cell proliferation causing Pruritus and flushing, diarrhea, and GERD

35
Q

What is the drug that reverses the physiological effects of histamine?

A

Epinephrine

36
Q

What are the three antihistamines that are release inhibitors of histamine?

A

Cromolyn
Nedocromil
Omalizumab

37
Q

H1 receptor antagonism is used for what? H2?

A

H1 =Allergies

H2 = Gastric acid secretion

38
Q

What are the H2 receptor antagonists?

A

Cimetidine and other-tidines

39
Q

What are the side effects of the 1st generation of antihistamines?

A

Ach inhibition
Alpha 1 inhibition
5HT Inhibition

40
Q

What are the three major symptoms that are treated with 1st gen antihistamines?

A

Rhinitis
Conjunctivitis
Urticaria

41
Q

What is the role of antihistamines in motion sickness?

A

Inhibit H1 receptors in the emetic center in the medulla

42
Q

What are the receptors in the emetic enter of the medulla?

A

H1
M
5HT3

43
Q

What does it mean when H1 antihistamines are inverse agonists?

A

bind and stabilize the inactive form of the histamine receptors

44
Q

What are the adverse effects of H1 antihistamines on the CNS?

A

Decreased alertness/sedation

45
Q

What are the adverse effects of H1 antihistamines in terms of the antimuscarinic effects?

A

Dry mouth
Urinary retention
Sinus tach

46
Q

What are the adverse effects of H1 antihistamines in the terms of the serotonin receptor agonization?

A

Increased appetite and weight gain

47
Q

What are the adverse effects of H1 antihistamines in terms of alpha adrenergic antagonism?

A

Dizziness

Postural hypotension

48
Q

What is the MOA of Chlorpheniramine? What is this used to treat?

A

1st gen antihistamine

Not an antiemetic, but allergies good

49
Q

What is the major 1st generation ethanolamines? What is this used to treat? Side effects

A

Diphenhydramine (benadryl)

Motion sickness and allergies, but causes sedation

50
Q

How does diphenhydramine work as a local anesthetic?

A

Blocks Na channels in excitable membranes

51
Q

What are the uses of Pyrilamine? MOA? Side effects?

A

Allergies

1st gen antihistamine

Low sedation, no antimuscarinic or motion sickness

52
Q

What is hydroxyzine used for? MOA? Side effects?

A

Antiemetic and anxiolytic

1st gen antihistamine

has a lot of antimuscarinic effects

53
Q

What is meclizine used for? MOA?

A

Motion sickness and vertigo

1st gen antihistamine

54
Q

What is the use of promethazine? MOA? Side effects?

A

Antiemetic and local anesthetic

1st gen antihistamine

Significant inhibition of alpha 1 adrenergic receptors and antimuscarinic effects

55
Q

Promethazine is similar in structure to what drug? What does this mean?

A

Chlorpromazine

Similar D2 antagonism, but lower potency

56
Q

What is Cyproheptadine? MOA? What is it used for?

A
  • Significant antiserotonin activity
  • 1st gen antihistamine

-Anti-5HT to treat serotonin syndrome and causes weight gain

57
Q

What are the four strongest antiemetic antihistamines?

A

Diphenhydramine
Promethazine
Hydroxyzine
Meclizine

58
Q

What are the three antihistamines that have the highest sedative effects?

A

Diphenhydramine
Hydroxyzine
Promethazine

59
Q

What antihistamine has a very strong anti adrenergic action? What are the side effects of this?

A

Promethazine-

Hypotension
Dizziness

60
Q

Which antihistamines have a strong anticholinergic effects? What are the side effects of this?

A

Diphenhydramine
Promethazine

Dry mouth
Urinary retention
Sinus tach

61
Q

Which antihistamine has a strong anti serotonin effect?

A

Cyproheptadine

62
Q

What class of drugs can intensify the anticholinergic effects of antihistamines?

A

MAOIs

63
Q

What drugs have an additive effect on antihistamine sedative effect?

A

EtOH
opioids
Sedatives

64
Q

True or false: most of the antihistamines are well absorbed in the GI tract

A

True

65
Q

What are the enzymes that metabolize first gen antihistamines?

A

CYP2D6 and CYP3A4

66
Q

What are the drugs that interact with p450s that antihistamines are metabolized by?

A

Imidazoles

Macrolides

67
Q

What are the second generation of antihistamines (6)?

A 
Azelastine
Cetirizine
Levocetirizine
Desloratadine
Loratadine
Fexofenadine
68
Q

What are the advantages of second generation antihistamines?

A

reduced lipophilicity

Higher selectivity

69
Q

What is Azelastine? Use?

A

2nd gen antihistamine that also Inhibits histamine release from mast cells

intranasal and ophthalmic

70
Q

What are the two second generation antihistamines that have high sedative effects?

A

Cetirizine

Levocetirizine

71
Q

Which 2nd gen antihistamine is minimally metabolized by the liver? Which is extensively metabolized by CYP3A4?

A

Fexofenadine

Loratadine

72
Q

True or false: 2nd gen antihistamine are generally greatly affected by liver or renal dysfunction.

Which one falls outside this commonality

A

False

Fexofenadine metabolism is affected by renal dysfunction

73
Q

Fexofenadine should be avoided while taking what drug? Why?

A

Antacids d/t reduced absorption

74
Q

Grapefruit juice causes what interaction with 2nd gen antihistamines? How?

A

Reduce bioavailability d/t inhibiting p-glycoproteins

75
Q

What is the MOA of Omalizumab? Use?

A

Recombinant humanized anti IgE

Treats chronic urticaria and asthma

76
Q

Which TCA inhibits H1 and H2 receptors? What is this used for?

A

Doxepin

Chronic urticaria

77
Q

What is the MOA and use of ketotifen?

A

H1 antihistamine with additional mast cell and basophils stabilizing properties

Allergic conjunctivitis

78
Q

What is the MOA of Cromolyn?

A

Prevents the release of histamine from mast cells through inhibition of Cl channels

79
Q

What is the MOA of nedocromil?

A

Prevents the release of histamine from mast cells through inhibition of Cl channels

80
Q

What are the two major differences between the first generation H1 antagonists and second generation?

A

1st generation his a lot of other receptors, and does not cross the blood brain barrier

Pharm (73 decks)

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