1st Generation H1 antihistamine Flashcards
Histamine H1 receptor antagonists (group) - MoA
bind to the H1 receptor and act as competitive receptor antagonists, and block most of the effects of histamine on vascular smooth muscles and nerves and thereby prevent or counteract allergic reactions
Histamine H1 receptor antagonists (group) - Clinical use
Allergic reactions (all are equally active for this), but differ markedly in their sedative, antiemetic and anticholinergic properties.
Histamine H1 receptor antagonists (group) - Interactions
Extensively metabolized by cytochrome P450.
1st generation antihistamines
Chlorpheniramine Clemastine Dimenhydrinate Diphenhydramine Hydroxyzine Meclizine Promethazine Doxepin Doxylamine with vitamin B6
1st generation antihistamines - MoA
Block cholinergic muscarinic receptors
1st generation antihistamines - Clinical use
Used to produce sedation
Treat: Nausea, vomiting, vertigo.
Prevention of motion sickness.
1st generation antihistamines - Administration and Contraindication (Caution)
Administered oral or parenteral
Caution for treatment of children
1st generation antihistamines - Adverse effects
Sedation Children and infants: cause excitement Dry mouth Blurred vision Tachycardia Urinary retention Hallucinations
Chlorpheniramine - Clinical use
Allergic reactions to pollen, mold, and other environmental allergens
Dimenhydrinate, Meclizine - Clinical use
Vertigo
Prevent motion sickness
Diphenhydramine, Hydroxyzine, Promethazine - Clinical use
Induce sleep, pre-op sedation.
Distress from severe pruritus
Doxepin - Clinical use
Antidepressant and anxiolytic effects
Insomnia treatment (low doses)
Induce sleep, preoperative sedation
Distress from severe pruritus
Doxylamine - Clinical use
With vitamin B6 for morning sickness in pregnant women
Which 1st generation antihistamines must be cautiously used against heavy machinery in patients taking the drug
Diphenhydramine
Hydroxyzine
Promethazine
Doxepin
