Anti-Histamines Review Flashcards
Describe the differences in pharamcology between first and second generation anti-histamines
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
What are the first generation anti-histamines?
1) Promethazine
2) Ethanolamines
a) Diphenhydramine
b) Doxylamine
c) Clemastine
3) Alkylamines
a) Chlorpheniramine
b) Bropheniramine
c) Dexbrompheniramine
d) Triprolidine
Rank the first generation anti-histamines in regards to sedation?
Promethazine > Ethanolamines > Alkylamines
Rank the first generation antihistamines in regards to anti-cholinergic properties?
Promethazine/Ethanolamines > alkylamines
What is a rare side effect that can occur in children with first gen antihistamines?
Paradoxical reaction
- Can make kids hyper rather than tired
- A rare reaction
Compare the critical side effects of first gneration anti-histamines to second generation anti-histamines
Second generation anti-histamines do not cause sedation as do not cross the blood brain barrier
How long does it take for second generation antihistamines to start working?
Act fast - Same as benadryl - One hour to start working
What is the dosing of second generation anti-histamines?
Mainly dosed OD (some are dosed BID) –> Fexofenadine (BID)
What are the second generation anti-histamines? Age of usage? Key facts?
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
