Rx Files Antihistamines Flashcards
What is the main role of blocking the H1 receptor?
anti-allergy
What is the main role of blocking the H2 receptor?
decrease GI acid secretion
Where are the H1 receptors found?
throughout the body
Where are the H2 receptors found?
throughout the body
On what do the sedation effects of antihistamines depend?
lipid solubility
What are some dangers of anti-cholinergic effects?
- angle closure glaucoma
- urinary tract obstruction
- dry mouth
- tachycardia
What is the mechanism of angle closure glaucoma?
fluid cannot be drained from the eye and pressure builds
Hydroxyzine HCl brand
Atarax
Hydroxyzine Pamoate brand
Vistaril
Is hydroxyzine sedating?
yes
What are the indications of hydroxyzine?
- anxiety
- post-op sedation
- antipruritic
- antiemetic
- alcohol withdrawal symptoms
Hydroxyzine adverse effects
- sedation
- thickening of bronchial secretions
- dry mouth
What is a usual dose of hydroxyzine?
- pruritis: 25 mg PO TID-QID
- seasonal rhinitis: 25 mg PO Qhs until no sedation in a.m.
Hydroxyzine (is/is not) recommended in the elderly.
is not
Which form of hydroxyzine is available IV?
HCl
Diphenhydramine brand
Benadryl
Is diphenhyramine a sedating antihistamine?
yes
Diphenhydramine indications
- allergy symptoms
- mild nighttime sedation
- motion sickness
- antitussive
- treatment of phenothiazine-induced dystonic reactions
- antinauseant
- topical anesthetic
Diphenhydramine adverse effects
- headache
- sedation
- dry mouth
Diphenhydramine dosing
- allergies: 25 - 50 mg PO q6-8h
- sedation: 50 mg qhs
Diphenhydramine can cause what in children?
hyperactivity
___ mg dimenhydrinate (Dramamine) = ___ mg diphenhydramine
100
50
Cetirizine brand
Zyrtec
Is cetirizine sedating?
no
Cetirizine indications
- seasonal allergies
- perennial allergies
- urticaria
Cetirizine adverse effects
- headache
- sedation
- dry mouth
Cetirizine dosing
5-10 mg daily
What age children can cetirizine be given?
> 6 months
Cetirizine is a metabolite of what?
hydroxyzine
What is the only antihistamine NOT metabolized by the CYP-450 system?
cetirizine
Loratadine brand
- Claritin
- Alavert
Is loratadine a sedating antihistamine?
no
Loratadine indications
nasal and non-nasal symptoms of allergic rhinitis
Loratadine adverse effects
- headache
- drowsiness
- fatigue
Loratadine dosing
- 10 mg PO daily
Desloratadine brand
Clarinex
Fexofenadine brand
Allegra
Is fexofenadine sedating?
no
Fexofenadine indications
relief of symptoms of seasonal allergic rhinitis
Fexofenadine adverse effects
- headache
- vomiting (children)
Fexofenadine dosing
60-180 mg PO BID
Fexofenadine is the active metabolite of
terfenadine
What are the sedating antihistamines?
- brompheniramine
- chlorpheniramine
- diphenhydramine
- doxylamine
- promethazine
- hydroxyzine
What are the non-sedating antihistamines?
- fexofenadine
- loratadine
- cetirizine
- levocetirizine
Pseudoephedrine brand
Sudafed
Pseudoephedrine mechanism of action
alpha-1 agonist
Pseudoephedrine adverse effects
- tachycardia
- hypertension
- decreased appetite
- increased energy
Pseudoephedrine dosing
30 - 60 mg PO q4-6h
max 240 mg/ 24 hours
