Autonomic Drugs-Sympathomimetic Amines (N-13) Flashcards
name the three naturally occurring catecholamines
EPI
NE
Dopamine
what is the basic structure of the sympathomimetic amine
B-(3,4-dihydroxyphenyl)-ethylamine.
name the three ways efficacy of a particular sympathomimetic amine is determined
concentration at the receptor site
affinity for specific receptors
population of receptors available for binding.
at low doses what receptors does epi stimulate
beta 1 and beta 2 receptors
what are the effects of myocardial demand and myocardial supply when administering EPI
it can increase myocardial demand and decrease myocardial supply.
what are the beneficial effects of Beta -2 stimulation with EPI
bronchodilation
vasodilation
stabilization of mast cells
decrease in histamine release
the beneficial effects of beta 2 and alpha stimulation of EPI will result in
alpha will result in decrease in bronchial secretions
net effect=decrease in airway resistance and improvement in oxygen
what is the result of Epinephrines beta 1 effects
+inotropic
+chronotropic
+dromotropic
if EPI is making the heart rate, left ventricular stroke work , stroke volume, and cardiac output increase- what happens to myocardial oxygen consumption
increases
with low dose EPI (10mcg/min) - why does SVR decrease
peripheral vasculature vasodilation- blood flow to skeletal muscles and decreases SVR
when EPI doses increase what effect predominates.?
systolic effect?
diastolic effect?
alpha
systolic increases
diastolic effect unchanged
what happens TRANSIENTLY followed by a LONGER EPI beta 2 stimulation to potassium
transient hyperkalemia
longer hypokalemia as beta 2 stimulation then forces this extracellular potassium into red blood cells.
what two drugs are considered first line therapy for shock
NE and dopamine
a meta analysis showed NE and dopamine to be equally effective for shock- - and dopamine increased what two issues
arrhythmias and possibly increased mortality
To a lesser extent than EPI- NE has some generalized metabolic effects such as
decrease in insulin production
what are the adverse effects usually seen with NE
intense vasoconstriction associated with NE
what type of sepsis does dopamine have a negative response to? and why?
gram negative sepsis- because the sensitivity of beta receptors is diminished due to a down regulation
dopamine inhibits “this” leading to increase in sodium excretion and urine output
aldosterone
why does dopamine increase renal blood flow, increase GFR, ad urine output.
it stimulates dopamine receptors in the renal arteries.
many clinicians have abandoned the renal dopamine dosing due to
lack of improvement in long term morbidity and mortality
dopamine has been implicated in several cases of severe limb ischemia-if administered through peripheral line- increase viligence is required for these 4 diseases
vascular diseases
diabetes
atherosclerosis
raynauds phenomenon
if a patient is receiving “this drug” dopamine can be prolonged
MAOI
which other type of drug can augment the activity of sympathomimetics drugs
tricyclic antidepressants
what effects of isoproterenol on the heart limits its use for heart block unresponsive to atropine
tachycardia
induction of MI
arrhythmia production
isoproterenol is a synthetic catecholamine, potent nonselective agonist of what 2 receptors
beta 1
beta 2
what is isoproterenol used for
bradycardia with heart block
torsades de pointes ventricular tachycardia
post heart transplant for chronotropic support
what are the cardiac and pulmonary effects seen with isoproterenol
potent bronchial dilator and pulmonary vasodilator
positive inotropic and chronotropic effects
dobutamine is a modification of what drug
isoproterenol
primarily dobutamine works on ___receptor with some effects on ____receptor
beta 1
some beta 2 effects
dobutamine induces what responses
strong inotropic response
minimal chronotrophy
