Mechanism of Action
- Blocks Histamine H1 receptors preventing bronchoconstriction and vasodilation.
- Blocks ACh receptor sites (anticholinergic)
- Also useful in reversing dystonic reactions caused by medications that block histamine receptor sites. (thorazine, compazine, reglan, haldol, phenergan)
- Moderate to severe allergic reactions
- Acute extrapyramidal reactions. (dystonia)
- Newborns and nursing mothers
- Not considered a primary drug for the treatment of severe allergic reactions or anaphylaxis
- Use caution in narrow-angle glaucoma
- Disturbed coordination
- Dry mouth
Potentiated by other CNS depressants, antihistamines, narcotics and alcohol. MAOIs may prolong or intensify the anticholinergic effects.
Dose and Route
- Adult: 25-50 mg IVP/IM q 6-8 hours
- Pedi: 1 mg/kg IVP/IO max single does 50 mg q 6-8 hours