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3 Basic histamine receptors
- 1. H-1-receptor: bronchospasm
- 2. H-2-receptor: gastric acid secretion, cutaneous vasodilation.
- 3. H-3-receptors: inhibits neurotransmitters in the CNS.
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Histamine is stored and released from...
- Mast cells
- Basophils
- CNS Neurons
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Physiologic effects of histamine release...
- Vasodilation
- localized reddening, edema, flare
- Bronchoconstriction
- Inc Chronotropy and Inotropy (heart rate & contratility)
- Pain, itchy
- Gastric acid secretion
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H1 Blockers
Action: Block vasodilation, itching, smooth muscle stimulation.
Uses: Prevent/Tx allergic reactions, prevent/Tx motion sickness.
ADE: Sleepiness, confusion, fatigue, vertigo, rash, blur, diplopia.
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Sedating Antihistamines are contraindicated when...
Narrow angle glaucoma, BPH, Peptic ulcer Dz, bladder obstruction.
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First generation Anti histamines...
Benadryl, et al.
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Sencond generation Anti histamines...
Zyrtec (Highly sedating) , et al.
- Non-sedating:
- Clartin, Alovert, Allegra, Clarinex
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H2 Blockers
Action: Dec gastric acid secretion, dec vasodilation.
Uses: PUD, GEARD, duodenal/gatric/stress uclers
- ADE: HA, Diarrhea, rash, heptic and renal impairment
- -Tagamet has worst ADE & D:D profile
- -Pepcid is in our scope of practice
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How long do you wait before inserting CLs???
-over use of topical antihistamines causes rebound vasodilation
10 min
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