Histamine, Serotonin & Ergot Alkaloids Chp 16 Flashcards
First Generation H1 antihistamines
Diphenhydramine
Effects of first generation antihistamines
reduces/prevents histamine effects on smooth muscle, immune cells; also blocks muscarinic and Alpha adrenoceptors; HIGHLY SELECTIVE
Action of first generation antihistamines
competitive antagonism/inverse agonism at H1 receptors
Clinical usage of first generation antihistamines
IG-E immediate allergies, especially hay fever, urticaria; often used as. a sedative, anti-emetic, and anti-motion sickness drug
Toxicity of Histamines first generation
sedation, muscarinic blockade s/s, orthostatic hypotension, some inhibition of CYP2D6, may prolong action of some beta blockers
What is a second generation antihistamine
Cetirizine
Action of 2nd generation antihistamines
competiitive antagonism/inverse agonism at H1 receptors
effects of cetiriizine
reduces/prevents histamine effects on smooth muscle, immune cells
Usage of second generation antihistamine
IG-E immediate allergies
Toxicity of 2nd generation antihistamines
sedation and arrhythmias in overdose
Serotonin Agonist
5-HT (1B/1D)
Example of 5-HT (1B/1D)Agonist
Sumatriptan
Action of Sumatriptan
partial agonist at 5-HT (1B/1D)receptors
Effects of sumatriptan
not fully understood; may reduce release of calcitonin gene-related peptide and perivascular. edema in cerebral circulation
Usage of Sumatriptan
Migraine and cluster HA