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
Toxicity of Sumatriptan
paresthesia, dizziness, coronary vasoconstriction
What is the importance of Histamines
mediator of immediate allergic and inflammatory reactions, modest role in anaphylaxis, gastric acid. secretion, and NT and neuromodulator, CV regulation, sleep and arousal, theraml and body wt. regulation
H4 blockers
has potential in chronic inflammatory conditions such as asthma, in which eosinophils and mast cells play a role
Brain serotonergic neurons are involved in…
mood, sleep, appetite, and temperature regulation, perception to pain, regulation of blood pressure and vomiting
Adverse effects of Histamines
Flushing, hypotension, tachycardia, HA, urticaria, bronchoconstrictions, and GI upset
H3 selective ligands
value in sleep disorders, narcolepsy, obesity, and cognitive and psychiatric disorders
Characteristics of COX 1
“house keeping” functions; gastric epithelial COX
Characteristics of COX 2
major source of prostanoids in inflammation and. cancer
Lipoxygenase Pathway
gives rise to leukotrienes; associated with asthma, anaphylactic shock, and CV disease; bronchoconstriction