sympathomimetic "drugs to read" Flashcards
dobutamine at higher does exerts its affects on which receptor
alpha
isoproterenol acts on which receptors
beta 1 beta 2
which medication is the most potent of all sympathomimetics
isoproterenol
what is the dose is isoproterenol IV infusion
1-5mcg/min
what are the effects seen with isoproterenol
increases hr, myocardial contractility, cardiac automaticity
and
vasodilation in skeletal muscles decreases SVR
myocardial oxygen requirements of isoproterenol
increased by tachycardia and contractility.
adverse effects of isoproterenol
vasodilation
decrease BP
tachyarrhythmias
MI (decrease BP, increase HR)
isoproterenol- uses
bradycardia
pul HTN
bronchodilator
which medication is derived from isoproterenol consisting of 50:50 racemic mixture
dobutamine
dobutamine (-) enantiomer receptors
potent alpha 1 agonist
weak beta 1 beta 2 agonist
dobutamine (+) enantiomers receptors
antagonist at alpha 1
potent b1 b2 agonist
at higher doses where does dobutamine exert its effects
on alpha receptors
dobutamine how does it increase cardiac output
positive inotropic agent
increases cAMP increasing calcium from SR
adverse effects of dobutamine
tachyarrhythmias
ST, ventricular arrhythmias
dobutamine prolonged continuous infusion concerns
eosinophilic myocarditis and peripheral eosinophilia
dobutamine clinical uses
CHF
weaning from bypass
PUL HTN
stress test
dobutamine half life
2 minutes
dobutamine infusion dose
2-10mcg/kg/min
dobutamine metabolism
biotransformation in the liver inactive glucoronide conjugates and 3-0 methyldobutamine- most of which is excreted in the liver
does tachyphylaxis occur with dobutamine
may occur as it acts on B-adrenergic receptors.
dopamine receptors
d1, d2, a and b
DOPAMINE EFFECTS
d1=
d2=
a1=
b1=
d1- vasodilation
d2- vasodilation
a1 vasoconstriction
b1- increases co
which receptors is associated with the reward receptor with dopamine
d2
dopamine at dose 0.5-3mg/kg/min
what is this dose used for
d1 & d2= vasodilation, decreased arterial BP,
diuresis and natriuresis
dopamine at 3-10mcg/kg/min
beta 1 and alpha receptors
norepinephrine release
increased cardiac output increasing chronotropy and contractility
dopamine > 10mcg/kg/min
acts similar to pure alpha agonist.
dobutamine renal blood flow effects
increases renal blood flow due to increase in cardiac output.
dobutamine effects less than 5mcg/kg/min
beta adrenergic agonist effects. increasing myocardial contractility and peripheral vasodilation.
how much variability does dopamine have
10-75 fold variability in plasma dopamine concentrations .
dopamine half life
1-2 minutes
how do we treat extravasion of dopamine
local infiltration of phentolamine
does dopamine cause CNS effects
no it does not cross the blood brain barrier
protein binding of dopamine
partially protein bound
is the “renal dose of dopamine” really protecting the kidneys?
diuretic effect-but not protective in the setting of low cardiac output. it does not improve creatinine clearance.
is dopamine recommended in right heart failure
no
what is concerning about a patient with glaucoma receiving dopamine infusion?
dopamine continuous infusion increases ocular pressure- concerns for patients with glaucoma
dopamine and respiratory effects
inhibitory NT to the carotid bodies- results in depression of ventilation and decreased 02
dopamine endocrine and immunologic effects.
suppress the secretion and function of anterior pituitary hormones
aggravating catabolism & cellular immune function
induces central hypothyroidism
what is the function of selective beta 2 adrenergic agonist
relax bronchiole and uterine smooth muscle.
do selective beta 2 stimulate the heart, which drug is the exception
no, isoproterenol
beta 2 agonist clinical uses
asthma, prevention of exercise induced asthma, COPD, stop premature uterine contractions
how much of a beta 2 is delivered from a MDI vs tracheal intubation
12% MDI
decrease 50-70% with ETT
how much more must be delivered for bronchodilation to occur for some intubated
6-10x what is used for an MDI
side effects of beta 2 inhalation
tremor increased HR hyperglycemia hypokalemia hypomagnesia lactic acidosis
albuterol - other name and dose
salbutamol
100mcg per puff
1-2 puff every 4-6 hours
in relation to intubation, how is albuterol helpful
it blunts airway responses to tracheal intubation in asthmatic patients.
metaproterenol- clinical uses
beta 2 agonist to treat asthma
terbutaline
receptor?
admin routes
beta 2 agonist
PO, sub q, inhalation
terbutaline sub q dose
0.25mg
terbutaline mdi dose
200mcg
3 examples of cardiac glycosides
digoxin, digitoxin, ouabain
digitalis- what are cardiac glycosides made from
naturally occuring- foxglove plant
digoxin clinical uses
svt, afib, aflutter,
uncommonly used for left ventricular contractility due to the availability of more potent less toxic drugs
how does digoxin work
it slows conduction down in the av node
what do we co administer with digoxin to limit the possibility of toxicity
propranolol or esmolol combined with digoxin
if a patient has been taking digoxin and the doctor wants to do direct current cardio version what is our concern for the patient?
they will have an increased risk of developing cardiac dysrhythmias including vfib
digoxin half life
peak after administration
1-2 days
2 hours
in the absence of renal dysfunction, what is the most frequent cause of digitalis toxicity
diuretics that cause potassium depletion.
during anesthesia what must we not do to avoid digitalis toxicity
hyperventilate the patient- when we hyperventilate the patient their potassium goes down0.5 per 10 decrease in pac02 leading to lethal arrhythmias.
why is cardiopulmonary bypass dangerous with digitalis toxicity
impaired renal function and electrolyte changes such as hypokalmiea, hypomangesia prepose patient to digitalis toxicity
early manifestation of digitalis toxicity
anorexia, nausea and vomiting
what is the most common ecg finding associated with death from digitalis toxicity
ventricular fibrillation
treatment of digitalis toxicity
correct hypokalemia, hypomangesia, hypoxemia
administer phenytoin, lidocaine, atropine to treat cardiac dysrhythmias
insert TVP if complete heart block present
what is the effect of an antacid for digitalis absorption
decreases absorption
fentanyl enflurane and isofnlurance do what in relation to digitalis
protect against digitalis enhanced cardiac automaticity
what does quinidine do to digoxin
increases the plasma concentration of digoxin
what do we consider calcium
potent inotrope
normal calcium levels
8.5-10.5mg/dl
normal ionized calcium
1-1.26
levosimendan moa
increases the sensitivity of the myocardium to calcium
levosimendan clinical uses
heart failure and preoperative reduces risk of kidney injury after cardiac surgery
