Exam 3 Flashcards
xfFunctional Histamine Antagonists
Epinephrine
Cromolyn Sodium
First Generation Antihistamines
Diphenhydramine
Meclizine
Promethazine
Second Generation Antihistamines
Cetirizine
Fexofenadine
Decongestants
Phenylephrine
Antihistamine Drug General Mechanism
H1 Receptor Antagonist
Histamine Receptors
H1, 2, 3, 4
H1 Is the Most Clinically Relevant
Immune Cells That Release Histamine
Mast Cells in Tissues
Basophils in Blood
Mast Cell Priming
Ig E release from immune response binds to mast cells
Antigen binds to IgE upon subsequent exposure and causes mast cells to degranulate
GI Cells That Release Histamine
Enterochromaffin Like Cells or G Cells
Release histamine that acts on H2 receptors
Histamine Receptor Affinity
10 fold preference for H1
Three Components of Histamine Reaction
Vascular Smooth Muscle Dilation
Increased Vascular Permeability
Peripheral Sensory Nerve Excitation
General Role of Histamine in Asthma
Bronchiole hypersensitivity to histamine
Epinephrine alpha1 Receptor Activation
Vasoconstriction
Epinephrine beta2 Receptor Activation
Bronchodilation
Cromolyn Sodium Mechanism of Action
Inhibits lung mast cells release
Cromolyn Sodium Usage
Prophylactic use in asthma and hay fever
First Gen Antihistamine Adverse Effects
Enter the CNS
Anticholinergic Effects
GI Problems
Second Gen Antihistamine Adverse Effects
Mostly do not enter CNS
Less sedating than first gen
Less muscarinic action than first gen
More drug interactions through CYP 3A4 metabolism
First Gen Antihistamine Pharmacokinetic
Orally Available
Half life 4 to 6 hours
Second Gen Antihistamine Pharmacokinetics
Orally available
Half life 12 to 24 hours
Antihistamine Excretion
Urine
Feces for Fexofenadine
Antihistamine Therapeutic Usage
Relief of seasonal allergy symptoms
Best used prophylactically
Does not reduce edema once it has formed
Antihistamines for Use in Vestibular Disorders
Promethazine
Diphenhydramine
Meclizine
Antihistamines for Use as an Antiemetic
Promethazine