Anti-inflamm Antiallergic Immunologic Drugs- pharm

Histamine h1 antagonists have similar antihistamine

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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 groups: groups: – First-generation H1 antagonists (highly sedating) used for people with mild hay fever Ex: benadryl 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 Pharmacologic effects – 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 Overdose – CNS stimulation – Convulsions – Very young children especially sensitive H1 Antagonists Therapeutic uses – Mild allergy – Motion sickness – Insomnia – Common cold H1 Antagonists Adverse effects – Sedation – Nonsedative CNS effects Dizziness, fatigue, coordination problems – Gastrointestinal effects Can cause nausea, vomiting, loss of appetite, Can constipation constipation – Anticholinergic effects Weak atropine-like effects – Cardiac d...
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