Anti-Histamines Review Flashcards

1
Q

Describe the differences in pharamcology between first and second generation anti-histamines

A

First gneration anti-histamines can hit numerous histamine receptors (H1,2,3,4 and cholinergic receptors)

The H1 receptor is the receptor responsible for allergy symptoms; H2 is in the stomach

Second gneration anti-histamines have 1000x more affinity for the H1 receptor; more specific and less dirty pharamcology

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2
Q

What are the first generation anti-histamines?

A

1) Promethazine

2) Ethanolamines
a) Diphenhydramine
b) Doxylamine
c) Clemastine

3) Alkylamines
a) Chlorpheniramine
b) Bropheniramine
c) Dexbrompheniramine
d) Triprolidine

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3
Q

Rank the first generation anti-histamines in regards to sedation?

A

Promethazine > Ethanolamines > Alkylamines

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4
Q

Rank the first generation antihistamines in regards to anti-cholinergic properties?

A

Promethazine/Ethanolamines > alkylamines

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5
Q

What is a rare side effect that can occur in children with first gen antihistamines?

A

Paradoxical reaction

  • Can make kids hyper rather than tired
  • A rare reaction
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6
Q

Compare the critical side effects of first gneration anti-histamines to second generation anti-histamines

A

Second generation anti-histamines do not cause sedation as do not cross the blood brain barrier

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7
Q

How long does it take for second generation antihistamines to start working?

A

Act fast - Same as benadryl - One hour to start working

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8
Q

What is the dosing of second generation anti-histamines?

A

Mainly dosed OD (some are dosed BID) –> Fexofenadine (BID)

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9
Q

What are the second generation anti-histamines? Age of usage? Key facts?

A

Loratidine (Claritin) - 2 years old
Desloratidine (Aerius) - 2 years old
Cetirizine (Reactine) - 2 years old
Fexofenadine (allegra) - 12 years old

  • Reactine is more sedating than the rest
  • Fexofenadine - D.I. with grapefruit/orange and apple juice + when taken with food
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