Antihistamines (Exam #2) Flashcards

1
Q

First Generation H1 Antagonists vs. Second Generation H1 Antagonists (think penetration/effect, AEs)?

A

1st Gen: ENTERS BRAIN = sedating
- AEs involve blocking muscarinic receptors (DRY)

2nd Gen: NON-sedating
- Fewer AEs because no blocking of muscarinic receptors

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2
Q

What are the three FIRST Generation H1 Antagonists? What do they all have in common?

A

SEDATING

  • Diphenhydramine (Benadryl)
  • Dimenhydrinate (Dramamine)
  • Promethazine (Phenergan)
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3
Q

What are the three SECOND Generation H1 Antagonists? What do they all have in common?

A

NON-sedating

  • Loratadine (Claritin)
  • Certirizine (Zyrtec)
  • Fexofenadine (Allegra)
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4
Q

Which antihistamine drug CAN be used in patients with liver disease, and why?

A

Certirizine (Zyrtec)

- Excreted by kidney

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5
Q

What are the two NASAL H1 Antagonists?

A
  • Cromolyn

- Azelastine (Astelin NS/Astepro)

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6
Q

Which three antihistamines can be used to treat motion sickness, and why?

A

FIRST Generation H1 Antagonists = antimuscarinics

  • Diphenhydramine (Benadryl)
  • Dimenhydrinate (Dramamine)
  • Promethazine (Phenergan)
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7
Q

Which antihistamines are CI in children?

A

FIRST Generation H1 Antagonists (Diphenhydramine (Benadryl), Dimenhydrinate (Dramamine), Promethazine (Phenergan))

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8
Q

What specific AEs are seen with ALL antihistamines (oral vs. topical)?

A
  • Oral: GI issues

- Topical: allergic reactions

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9
Q

How might overdose of FIRST Generation H1 Antagonists present? SECOND Generation H1 Antagonists?

A
  • First = atropine poisoning (excitement, convulsions, ataxia, hallucinations, tremors, fixed pupil dilation)
  • Second = cardiac arrhythmias
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10
Q

Which inhaled form of antihistamines inhibits release of histamine from mast cells? What other drug might do this too?

A

Cromolyn

- Ceterizine (Zyrtec) also inhibits release of histamine from mast cells

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11
Q

Which inhaled form of antihistamines is a non-competitive H1 blocker?

A

Azelastine (Astelin NS/Astepro)

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12
Q

Which three classes/drugs should be avoided with antihistamines? What else?

A

AVOID:

  • Erythromycin
  • Ketoconazole
  • CNS depressants
  • Grapefruit juice (CYP3A4 inhibitor → increase concentration of drugs)
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13
Q

Which antihistamine drug is also used as a sleep aid?

A

Dimenhydrinate (Dramamine, Tylenol PM)

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14
Q

What is the recommended tx for anaphylactic shock (4)?

A
  • Epi
  • Steroids
  • H1 antagonists
  • H2 antagonists
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15
Q

What unwanted effect of H1 antagonist antihistamines may be seen in asthmatics, and why?

A

Bronchospasm

- Increase Ca2+

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