1 / 6

H1 Antagonists

H1 Antagonists. reversible competitive inhibitors well absorbed from the GI tract; peak plasma concentrations are achieved in 2 to 3 hours, and effects usually last 4 to 6 hours induce hepatic cytochrome P450 enzymes. H1 Antagonists.

baruch
Télécharger la présentation

H1 Antagonists

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. H1 Antagonists • reversible competitive inhibitors • well absorbed from the GI tract; peak plasma concentrations are achieved in 2 to 3 hours, and effects usually last 4 to 6 hours • induce hepatic cytochrome P450 enzymes

  2. H1 Antagonists • Primarily effective against cutaneous effects of anaphylaxis • Edema formation and itch - effectively suppressed. • Hypotension - less well antagonized (Gelfand, et al., 2004; Campbell and Harder, 1999) • Bronchoconstriction - reduced little, if at all.

  3. H1 Antagonists: 1st generation • Diphenhydramine • significant antimuscarinic activity (drying and thickening of oral and other respiratory secretions) and have a pronounced tendency to induce sedation

  4. H1 Antagonists: 2nd generation • Loratadine, Cetirizine • Less lipid-soluble and enter the central nervous system with difficulty or not at all • absorbed rapidly from the GI tract and metabolized in the liver to an active metabolite by the hepatic CYPs • excreted primarily into the urine as unmetabolized form

  5. Recommendation • Adjuvant to epinephrine • no evidence from randomized controlled trials to support the use of H1-antihistamines in the emergency management of anaphylaxis • should be administered for all patients with anaphylaxis or generalized urticaria • continued for 2-3 days after treatment of the acute anaphylactic event

More Related