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Pharmacology - Exam 3 > Anti-histamines > Flashcards

Anti-histamines Flashcards

1
Q

What are the 1st generation H1 antagonists?

A

Chlorpheniramine (Chlortrimeton)
Diphenhydramine (Benadryl)
Dimenhydrinate (Dramamine)

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2
Q

What are the 2nd generation H1 antagonists?

A

Loratadine (Claritin)
Cetirizine (Zyrtec)
Fexofenadine (Allegra)

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3
Q

How is histamine synthesized?

A

Decarboxylation of L-histidine by histidine decarboxylase

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4
Q

What is an autacoid?

A

Compounds that are released and act locally in periphery

Includes histamine, serotonin, prostaglandins, leukotrienes and kinins

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5
Q

What are the roles of histamine?

A

Immune response
Control stomach acid
Neurotransmitter

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6
Q

What is the distribution of histamine in the body?

A

Periphery: widespread (esp skin, lungs), most synthesized and stored in mast cells and basophils
Gastric Mucosa: In enterochromaffin-like cells (ECL) of stomach fundus
CNS: NTs in cell bodies of histaminergic neurons in ventral posterior hypothalamus

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7
Q

Histamine receptors are what kind of receptors?

A

G-protein coupled

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8
Q

Histamine in the smooth muscle, endothelium and CNS are received by what receptor subtype?

A

H1

Postreceptor response is Increase in…IP3, DAG, Ca2+, NO, cCMP (Gq)

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9
Q

Histamine in the gastric mucosa, cardiac muscle, vascular smooth muscle, mast cells and CNS is received by what receptor subtype?

A

H2

Postreceptor response is increase in cAMP (Gs)

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10
Q

Allergic reactions are what type of immune response?

A

Type I Hypersensitivity

via IgE: antigen crosslinking

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11
Q

Complement system activation releasing histamine from mast cells at a specific site causes what?

A

Inflammation

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12
Q

What kind of histamine release is caused by physical or chemical injury to skin or mucosa?

A

Mechanical release

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13
Q

What effect on histamine release does opioids have?

A

Opioids stimulate histamine release

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14
Q

What effect on histamine release does epinephrine/cromolyn have?

A

Blocks release

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15
Q

Does histamine action on smooth vessels (contraction) or endothelial cells (relaxation) win out in overall effect in the lungs?

A

Endothelial so overall action is relaxation in the lungs

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16
Q

What is felt upon stimulation of primary afferent nerve endings by endogenous histamine?

A

Itch

Pain

17
Q

Histamine as a NT in the ventral posterior hypothalamus helps regulate what functions?

A

Arousal (wakefulness)
Appetite
Body Temperature

18
Q

What spoiled food can cause histamine toxicity and what can suppress it?

A

Scombroid fish
Bacteria in fish metabolize histadine to histamine
Suppressed by H1 receptor blockers

19
Q

Are anaphylaxis symptoms caused primarily by histamine?

A

No

20
Q

Are local allergic reaction symptoms caused primarlily by histamine?

A

Yes
Urticaria
Allergic rhinitis

21
Q

What drug for allergies acts by directly inhibiting mast cell degranulation?

A

Cromolyn sodium

Available as nasal spray, inhaler or eye drops

22
Q

Do 1st gen or 2nd gen H1 antihistamines penetrate the blood brain barrier?

A

1st gen

23
Q

What is a common side effect of 1st gen H1 antihistamines?

A

Sedation

24
Q

In allergic rhinitis, 2nd gen antihistamines are least effective for:

  1. itching
  2. nasal congestion
  3. rhinitis
  4. sneezing
A
  1. nasal congestion
25
Q

Can H1 antihistamines be used in event of anaphylactic reactions?

A

No

26
Q

Are 1st gen or 2nd gen H1 antihistamines longer lasting?

A

2nd gen

27
Q

Where are H1 antihistamines metabolized and then cleared?

A

Metabolized in liver

Renal clearance

28
Q

Which H1 antihistamine is inhibited by grapefruit/orange/apple juice due to being transposted by intestinal OATP1A2?

A

Fexofenadine

29
Q

1st gen H1 antihistamines can have what cardiac adverse effects?

A

Dose related sinus tachycardia, reflex tachycardia

30
Q

What are contraindications for 1st gen H1 antihistamines?

A

Glaucoma, prostatic hypertrophy

Pharmacology - Exam 3 (12 decks)

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