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Unformatted text preview: minor role Leukotrienes are the principal mediators Antihistamines are of little use in treatment Epinephrine is the drug of choice for treatment
Epinephrine Histamine Antagonists
Histamine Antihistamines, histamine antagonists, and
Antihistamines, histamine blockers are used interchangeably.
histamine H1 antagonists have similar antihistamine
actions but differ significantly in side effects.
actions H1 antagonists are divided into two major
– First-generation H1 antagonists (highly
sedating) used for people with mild hay fever
Ex: – Second-generation H antagonists H1 Antagonists
Mechanism of action
– Block the actions of histamine at H1 receptors
– Do not block H2 receptors
– Some bind to muscarinic receptors H1 Antagonists
– Peripheral effects Reduce localized flushing Reduce itching and pain – Effects on the CNS Therapeutic dose – CNS depression – Second-generation negligible CNS depression Overdose can make you hyperactive
– CNS stimulation
– Very young children especially sensitive H1 Antagonists
– Mild allergy
– Motion sickness
– Common cold H1 Antagonists
– Nonsedative CNS effects Dizziness, fatigue, coordination problems – Gastrointestinal effects Can cause nausea, vomiting, loss of appetite,
constipation – Anticholinergic effects Weak atropine-like effects – Cardiac d...
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- Spring '14