Antihistamines Flashcards
what is the important mediator in inflammation?
mast cells and basophils
in the metabolism of histamine all forms are found what?
inactive
in the localization of histamine releasing cells, histamine is complexed with what particular storage granule?
heparin sulfate
what is the mechanism of histamine release?
binding of antigen to antibody molecules causes increase in cytoplasmic Ca2+ concentration
what drugs prevent histamine release and their dosage forms?
Cromolyn sodium
–> Rx- mastocytosis (oral)
–> OTC- allergic rhinitis (nasal spray)
how many histamine receptors are there?
4
where are H1 receptors distributed?
throughout CV, respiratory systems G.I smooth muscle
where are H2 receptors distributed?
in the CV system and GI smooth muscle and stomach
describe the H1 and H2 colocalization:
H1 in vascular endothelium : Inc. NO and contraction of endothelial cells
H2 in vascular muscle: relaxation (vasodilation)
how are H3 receptors distributed?
located mainly in the CNS–> coupled to Gi/Go
what are H1 antagonists referred to as?
antihistamines
how are H4 cells distributed?
located in mast cells, basophils, and eosinophils–> coupled to Gi/Go
what are H2 antagonists referred to as?
acid blockers
h1 antagonists are predominately what?
inverse agonists
what are the 1st gen antihistamines and their class?
- Bropheniramine –> alkylamine
- Cyproheptadine –> piperadine
- Diphenhydramine –> ethanolamine
- Promethazine –> phenothiazine
- Hydroxyzine –> piperazine
- Pyrilamine –> elenediamine