14 Antihistamines Flashcards

1
Q

which inflammatory cytokines do tissue cells release in times of stress or injury, or in response to T-cell cytokines?

A

IL-1, IL-6

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2
Q

What do phagocytes release in response to inflammatory stimuli?

A

inflammatory cytokines TNFalpha, IL-1, and IL-6; cytotoxic agents; proteases for degrading tissue; and lipid mediators to enhance local inflammation

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3
Q

What is the effect of inflammatory cytokines in the hypothalamus? in the liver?

A

in the hypothalamus, cytokines produce fever, and in the liver they induce the acute phase response

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4
Q

which class of drugs commonly target the cytokines that promote inflammatory activity (TNFalpha, IL-1)?

A

Disease-modifying antirheumatic drugs (DMARDS)

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5
Q

Infliximab, adalimumab, and etantercept are all examples of what type of drug?

A

Anti-TNFalpha agents

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6
Q

What are anti-TNFalpha agents and what is their mechanism of action?

A

anti-TNFalpha agents are either antiTNFalpha antibodies (infliximab and adalimumab) or other proteins (etanercept) that bind to TNFalpha to prevent its interaction with its receptor

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7
Q

what are the therapeutic applications of anti-TNFalpha agents, and what is the typical route of administration?

A

often used to treat rheumatoid arthritis and Crohn’s; parenteral administration is required

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8
Q

what is the main complication associated with anti-TNFalpha agents?

A

increased susceptibility to infection, especially upper respiratory and urinary infections

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9
Q

what type of drug is anakinra and what is its mechanism of action?

A

anakinra is an anti-IL1 agent that is a competitive IL-1 receptor antagonist

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10
Q

what type of drug is tofacitinib and what is its mechanism of action?

A

tofacitinib is a Jak kinase inhibitor that inhibits all activity of cytokines required for adaptive immunity

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11
Q

what are the therapeutic applications of anti-TNFalpha agents, and what is the typical route of administration?

A

often used to treat rheumatoid arthritis and Crohn’s; parenteral administration is required

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12
Q

What causes mediator release from activated leukocytes?

A

Lipid mediators are released in response to signals that activate phospholipase A2

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13
Q

How does phospholipase A2 cause the release of lipid mediators from leukocytes?

A

PLA2 hydrolyzes membrane phosphatidylcholine to release arachidonic acidAA is the substrate for production of lipid mediators of inflammation – cyclooxegenases produce prostaglandins, and lipoxygenases produce leukotrienes.

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14
Q

T or F: Stored mediators such as histamine are released from leukocytes in response to signals that activate phospholipase C

A

T

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15
Q

T or F: annexins/lipocortins inhibit PLC activity

A

F; they inhibit PLA2

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16
Q

What class of drugs inhibit cyclooxygenase, and what effect does this produce?

A

NSAIDS; decreased production of prostaglandin

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17
Q

What drug inhibits lipoxygenase, and what effect does it produce?

A

Zileuton; decreased production of prostaglandins

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18
Q

Cromolyn and nedocromil both inhibit which process?

A

They inhibit PLC mediated degranulation of stored mediators from leukocytes

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19
Q

What do glucocorticosteroids inhibit, and what effects do they produce?

A

Glucocorticosteroids inhibit PLA2 to reduce production of prostaglandins and leukotrienes, and they also inhibit production of chemotactic factors, which results in decreased recruitment of leukocytes

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20
Q

Glucocorticosteroids induce transcription of which gene, and why?

A

Induce transcription of annexins/lipocortins, which inhibit PLA2

21
Q

T or F: Glucocorticosteroids reduce leukocyte recruitment and mediator release by inducing transcription of various genes, such as those for cyclooxygenase, interleukins, and chemotaxins

A

F; it represses transcription to produce those effects

22
Q

What is the precursor for histamine synthesis, and what enzyme is used to convert it into histamine?

A

Histidine decarboxylase converts histidine to histamine

23
Q

Explain the two step degradation of histamine to methylimidazole acetic acid, including the enzymes involved.

A

1) Imidazole-N-Methyltransferase converts histamine to methylhistamine2) Diamine oxidase converts methylhistamine to methylimidazole acetic acid

24
Q

Which enzyme converts histamine to imidazoleacetic acid?

A

Diamine oxidase

25
Q

What are the two possible breakdown products of histamine degradation?

A

Methylimidazole acetic acid and imidizoleacetic acid

26
Q

Histamine intolerance results from deficiency of which enzyme?

A

Diamine oxidase

27
Q

What Histamine receptor subtypes are present on vascular smooth muscle, and what effects and resulting symptoms do they produce?

A

Receptor: H1, H2Effects: induces NO release to promote smooth muscle relaxation and vasodilationSymptoms: hypotension, flushing, headache, anaphylaxis

28
Q

What Histamine receptor subtypes are present on the vascular endothelium, and what effects and resulting symptoms do they produce?

A

Receptor: H1Effects: induces actin/myosin contraction which results in separation of endothelial cellsSymptoms: edema

29
Q

What Histamine receptor subtypes are present on cardiac muscle, and what effects and resulting symptoms do they produce?

A

Receptor: H1, H2Effects: H1 decrease heart rate and atrial contractility, and H2 increase rate and contractilitySymptoms: unknown

30
Q

What Histamine receptor subtypes are present on bronchiolar smooth muscle, and what effects and resulting symptoms do they produce?

A

Receptor: H1Effects: constriction of smooth muscleSymptoms: difficulty breathing due to airway constriction

31
Q

What Histamine receptor subtypes are present on uterine smooth muscle, and what effects and resulting symptoms do they produce?

A

Receptor: H1Effects: constriction of smooth muscleSymptoms: premature labor, anaphylaxis

32
Q

What Histamine receptor subtypes are present on gastric smooth muscle, and what effects and resulting symptoms do they produce?

A

Receptor: H1Effects: constriction of smooth muscleSymptoms: diarrhea

33
Q

What Histamine receptor subtypes are present on sensory nerves, and what effects and resulting symptoms do they produce?

A

Receptor: H1Effects: stimulation of neuronsSymptoms: pain, itching

34
Q

What Histamine receptor subtypes are present on the hypothalamus, and what effects and resulting symptoms do they produce?

A

Receptor: H1Effects: arousalSymptoms: increased wakefulness

35
Q

What Histamine receptor subtypes are present on the emetic center in the CNS, and what effects and resulting symptoms do they produce?

A

Receptor: H1Effects: emesisSymptoms: nausea, vomiting

36
Q

What Histamine receptor subtypes are present on the CNS in general, and what effects do they produce?

A

Receptor: H1, H2Effects: effects on thirst, BP control, and pain perception

37
Q

What Histamine receptor subtypes are present on gastric secretory cells, and what effects and resulting symptoms do they produce?

A

Receptor: H2Effects: increased pepsin, intrinsic factor, and acid productionSymptoms: mucosal erosion and ulceration

38
Q

What are the typical cutaneous signs of the histamine triple response?

A

Wheal and flare response, redness, itching

39
Q

What are physiological antagonists, and what is an example of a physiological antagonist for histamine?

A

Agents that have opposing effects on smooth muscle but are mediated through different receptors; An example for histamine is epinephrine

40
Q

What are release inhibitors, and what are some examples of release inhibitors of histamine?

A

Inhibitors that prevent degranulation of a substance; examples include cromolyn and nedocromil

41
Q

What are the main clinical uses of H1 receptor antagonists?

A

Allergic rhinitis and uticaria and motion sickness/emesis

42
Q

What is the main adverse affect that results directly from inhibition of H1 receptors?

A

Sedation due to CNS depression

43
Q

T or F: many first generation H1 receptor antagonist have non-H1 adverse effects due to their similarity to other drug classes, such as anticholinergics and antiadrenergics.

A

T

44
Q

What is the difference between first and second generation antihistamines?

A

Second gen antihistamines have higher selectivity for H1 receptors and penetrate poorly into the CNS, and so have less sedative effects and non H1 effects

45
Q

What type of drug is diphenhydramine, and what are its major effects and uses?

A

It is a first generation antihistamine; it has a strong sedative effect and is used for motion sickness

46
Q

What type of drug is dimenhydrinate, and what are its major effects and uses?

A

It is a first generation antihistamine; it has a strong sedative effect and is used for motion sickness

47
Q

What type of drug is cyclizine, and what are its major effects and uses?

A

It is a first generation antihistamine; it has a slight sedative effect and is used for motion sickness

48
Q

What type of drug is promethazine, and what are its major effects and uses?

A

It is a first generation antihistamine; it has a strong sedative effect and is used as an antiemetic

49
Q

Loratidine, cetirizine, and fexofenadine all belong to which class of drugs?

A

Second generation antihistamines