Autacoids Flashcards
what drugs can displace histamine from the heparin-protein complex within cells
morphine and tubocurarine
H1 and H2 – who has the higher affinity for histamine and its significance
H1 – rapid response but short lived
H2 – slowly develops response but sustained
what does activation of H1 and H2 lead to
H1 – works on endothelial cells so leads to production of NO
H2 - works on vascular SM so leads to vasodilation, in heart leads to increased contractility
histamine agonist and its clinical use
histamine
pulmonary function testing (test nonspecific bronchial hyperactivity)
toxicity of histamine
flushing, hypotension, tachycardia, headache, wheals (area of skin that is raised and itchy), GI upset, bronchial constriction
who do you not give histamine to
asthmatics, those with acute ulcer disease, GI bleeding
physiological antagonist of histamine
epinephrine
release inhibitors of histamine
cromolyn and nedocromil (use to treat asthma)
beta 2 agonists as well
what are the first generation H1 receptor antagonist
chlorpheniramine, cyclizine, dimenhydrinate, diphenhydramine, meclizine, promethazine, hydroxyzine
CD2 MPH
what are the second generation H1 receptor antagonist
cetirizine, fexofenadine, loratadine, astemizole, terfenadine
C-FLAT
why were astemizole and terfenadine removed from US market
induced potentially fatal arrhythmias called torsades de pointes
this occurred especially in the presence of CYP3A4 inhibitors leaving these two drugs in circulation longer than they are supposed to be
actions of H1 receptor antagonist
- inverse agonist
- blocks histamine induced contraction of GI and bronchial
- bind to cholinergic, alpha adrenergic, serotonin, and local anesthetic receptor sites
what are H1 receptor antagonists used for
- allergies caused by antigens acting on IgE antibody sensitized mast cells so like allergic rhinitis and urticaria
- not good at treating bronchial asthma because histamine is only one of the several mediators
- motion sickness and nausea (with scopolamine)
- insomnia
which antihistamine is used as a somnifacients aka tx for insomnia
diphenhydramine
which antihistamine is used as a tx for motion sickness and nausea
diphenhydramine, dimenhydrinate, promethazine
adverse reaction of H1 blocker
sedation and dry mouth
why is driving and operating heavy machinery cautioned against in H1 blockers
some H1 blockers cause sedation especially if taken with drugs that cause CNS depression
adverse effects if overdosed on H1 blockers
hallucinations, excitement, ataxia, and convulsion
what are H2 receptor antagonists
Famotidine, Ranitidine, Nizatidne, Cimetidine
FRaNC
clinical use of H2 receptor antagonist
inhibit gastric acid secretion (induced by histamine or gastrin)
so used for the treatment of peptic ulcer, acute stress ulcers, GERD
adverse effects of H2 blocker (we’ll talk about cimetidine in a diff flash card)
headache, diarrhea, muscular pain, constipation
- mental status changes
- blood dyscriasis
- bradycardia and hypertension
adverse effects of cimetidine an H2 blocker
- inhibits CYP450 and slows metabolism of certain drugs
- binds to androgen receptors and has antiandrogenic effects like gynecomastia in men and galactorrhea in women
what are the serotonin agonists
serotonin, sumatriptan, metoclopramide, cisapride
what is sumatripan used to treat
migraine headache (first line therapy for acute migraine)
who do you not prescribe sumatripan to and why
person with coronary heart disease because of their vasoconstrictive action
what is metoclopramide given for
prokinetic agent - enhance GI motility by coordinating contractions that enhance transit
adverse effects of metoclopramide
somnolence, nervousness, dystonic reactions
extrapyramidal effects and tardive dyskinesia
use of cisapride
prokinetic agent - enhance GI motility for pts with gastroesophageal reflux and gastroparesis
why is cisapride no longer widely used in US
because of its cardiac effects
what is the serotonin 5-HT2 antagonist
cyproheptadine
action of cyproheptadine
prevents smooth muscle effects of serotonin and histamine
uses of cyproheptadine
perennial and seasonal allergic rhinitis
vasomotor rhinitis
allergic conjuctivitis due to inhalant allergens and foods
cold urticaria
dermatographism
serotonin syndrome (hyperthermia, muscle rigidity, and myoclonus)
what is the serotonin 5-HT3 antagonist
ondansetron
use of ondansetron
nausea and vomiting that occurs with cancer chemotherapy
what are the ergoid alkaloids (also serotonin antagonist)
MEED CB
methylergonovine, ergonovine, ergotamine, dihydroergotamine, cabergoline, bromocriptine
ergoid alkaloid used to treat migraine
ergotamine
ergoid alkaloid used for hyperprolactinemia
bromocriptine and cabergoline
ergoid alkaloid used for postpartum hemorrhage
ergonovine and methylergonovine
what is used to diagnose variant angina (also do you remember what type of drugs you don’t use on pt with variant angina)
ergonovine to diagnose
do not use beta blockers on variant angina!
