Antihistamines Flashcards Preview

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Flashcards in Antihistamines Deck (12):
1

Diphenhydramine

- first generation
- marked sedation; anti-motion sickness (but not as good as Scopolamine); antitussive; OTC sleep aid

2

Pyrilamine

- first generation
- moderate sedation; OTC sleep aid

3

Hydroxyzine

- first generation
- marked sedation

4

Chlorpheniramine

- first generation
- OTC cold remedy; slight sedation

5

Promethazine

- first generation
- marked sedation; anti-emetic

6

Fexofenadine

- second generation
- metabolite of Terfenadine, originally removed from the market because of risk of QT prolongation and cardiac arrhythmias

7

Loratadine

- second generation

8

Cetirizine

- second generation

9

Cimetidine

- H2 antagonist
- OTC
- significantly increases bioavailability of ethanol by inhibiting gastric first-pass metabolism
- drug interactions via CYP450 metabolism (warfarin, phenytoin, TCAs, metronidazole, etc)
- adverse effects:
1. CNS delirium and confusion particularly in the elderly
2. Antiandrogenic effects - gynecomastia, galactorrhea, reduction in sperm count and reversible impotence
3. Blood dyscrasias
4. Common to all H2 blockers - diarrhea, dizziness, somnolence, headache, rash, liver toxicity (elevated liver enzymes)

10

Ranitidine

- H2 antagonist
- OTC
- less likely to interfere with CYP450 drug metabolism than Cimetidine
- significantly increases bioavailability of ethanol by inhibiting gastric first-pass metabolism

11

Famotidine

- H2 antagonist
- OTC
- no effect on the bioavailability of ethanol

12

Nizatidine

- H2 antagonist
- OTC
- significantly increases bioavailability of ethanol by inhibiting gastric first-pass metabolism