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)
