Sympathomimetics and Sympatholytics Flashcards
1
Q
Which branches of the nervous system have ganglions?
A
Both the parasympathetic and the sympathetic
BUT NOT the somatic. All motor neurons are one long neuron
2
Q
The peripheral nervous system employs three neurotransmitters:
A
Acetylcholine
Norepinephrine
Epinephrine
3
Q
What are cholinergic receptors?
A
Regulate responses to Acetylcholine
4
Q
What are adrenergic receptors?
A
mediate response to epinephrine and norepinephrine
5
Q
Where are NM Receptors located?
A
6
Q
Where are Muscarinic Receptors located?
A
7
Q
Where are NN receptors located?
A
8
Q
What are the muscarinic target organs?
A
Eye (miosis)
Heart (decreased HR)
Lung (Bronchial constriction)
Bladder and Bowels
Sweat Glands
Sex organs (erection)
Blood vessels (vasodilation)
9
Q
Does parasympathetic stimulation cause vasodilation?
A
NO! Even though there are muscarinic receptors on blood vessels, there are NO ParaSNS nerves that terminate on blood vessels
These receptors only matter when we’re using drugs
10
Q
Epinephrine is specific to what receptors?
A
Alpha 1
Alpha 2
Beta 1
Beta 2
11
Q
Dopamine is specific to what receptors?
A
Alpha 1
Beta 1
Dopamine
12
Q
Norepinephrine is specific to which receptors?
A
Alpha 1
Alpha 2
Beta 1
13
Q
Where are alpha 1 receptors found?
A
Eyes (dilation)
Arterioles (vasoconstriction in the skin, viscera, and mucous membranes)
Sex organs (ejaculation)
Prostate and bladder
14
Q
Where are alpha 2 receptors found?
A
Presynaptic nerve terminals
Inhibit transmitter release
15
Q
Where are Beta 1 receptors located?
A
Heart (increased rate, contractility, and conduction)
Kidney (release of renin, which increases BP)
16
Q
Where are beta 2 receptors located?
A
Arterioles (dilation of arterioles in the heart, lungs, and skeletal muscles)
Bronchodilation
Uterus (relaxation)
Liver (glycogenolysis)
Skeletal muscle (contraction, glycogenolysis)
17
Q
Where are dopamine receptors located?
A
Kidney (dilate kidney vasculature)
18
Q
Which neurotransmitters act on Beta 2 receptors?
A
ONLY EPINEPHRINE
19
Q
Where is epinephrine released from?
A
The adrenal medulla, NOT neurons
20
Q
What are the naturally occurring catecholamines?
A
Epinephrine
Norepinephrine
Dopamine
21
Q
What cerebral effects does epinephrine cause?
A
NONE
it isn’t lipid soluble, so it doesn’t cross the BBB
22
Q
Which two adrenergic receptors effect the heart?
A
Alpha 1
Beta 1
23
Q
What determines epinephrine’s specificity for alpha or beta receptors?
A
The dose
beta receptors are more sensitive to lower epinephrine doses (inotropy dose)
Alpha 1 receptors are more sensitive to higher doses (pressor dose)
24
Q
A patient who takes a beta blocker develops a bronchospasm and you give them epinephrine. What will happen?
A
It will get worse.
Epinephrine causes bronchodilation via beta 2 receptors BUT it also stimulates bronchial alpha 1 receptors
If they’re on a beta blocker, you’ll get unopposed alpha 1 bronchoconstriction
25
What electrolyte changes does Epinephrine cause?
Beta 2 stimulation leads to increased transfer of potassium into cells, decreasing serum potassium
This is why a lot of patients with high pre-op anxiety come in with low K
BUT epinephrine also stimulates potassium release from the liver, so offsets most of the effect
26
Norepinephrine is a derivative of \_\_\_\_\_\_\_
and is the precursor of \_\_\_\_\_\_\_
dopamine
epinephrine
27
Which endogenous catecholamine exerts the strongest effect on BP and SVR?
Norepinephrine exerts a much stronger effect than epinephrine
28
What are the metabolic effects of norepinephrine?
Unlike epinephrine, there really aren't that many
Doesn't usually cause hyperglycemia
29
Is norepinephrine an inotrope?
yes and no
it acts on Beta 1 receptors to increase HR, contractility and conduction BUT it's alpha 1 action is so strong that the increased afterload may decrease CO
30
Does dopamine cross the BBB?
No. It's very polar.
31
What Dopamine dose rate stimulates D1 and D2 receptors?
0.5-3 mcg/kg/min
32
What happens when D1 and D2 receptors are stimulated?
Decreased BP
vasodilation
increased renal and splanchnic flow
Diuresis
Natriuresis
33
What dopamine dose rate stimulates Beta 1 receptors and alpha 1 receptors?
3-10 mcg/kg/min
34
What dopamine dose rate stimulates primarily alpha 1 receptors?
> 10 mcg/kg/min
35
Which hormones does Dopamine inhibit?
anterior pituitary hormones:
Prolactin (which causes immune problems)
GH (impaired anabolism)
central hypothyroidism
36
How does dopamine impact ventilation?
low dose dopamine interferes with pulmonary hypoxic vasoconstriction and raises the CO2 threshold
37
Name the synthetic catecholamines:
Isoproterenol
Dobutamine
38
**ISOPROTERENOL**
CLASSIFICATION & MOA
Synthetic catecholamine
Beta 1 and Beta 2 selective agonist
39
Which causes more reflex tachycardia: dobutamine or isoproterenol?
isoproterenol
both because of direct beta 2 effects and because it causes more vasodilation, causing reflexive increase from decreased vascular tone
40
**DOBUTAMINE**
CLASSIFICATION AND MOA
Synthetic Catecholamine
Racemic mixture derived from isoproterenol
Potent Beta 1 effects
Weak Beta 2 effects
Some alpha effects at high dose
41
What makes dobutamine an inotrope?
It increases cAMP, increasing Ca release from the SR and increasing contractility
42
Is blood pressure effected by dobutamine?
It usually isn't, because one enantiomer stimulates alpha 1, but the other antagonizes it
So usually the two equal out
43
How does dopamine impact pulmonary vasculature?
It does dilate, but not as much as phosphodiesterase inhibitors
44
Which is more dysrhythmogenic: dobutamine or dopamine?
Dopamine
45
Why does epinephrine results in increased lactate levels?
Decreased splanchnic flow means decreased lactate metabolism
46
There are two synthetic noncatecholamine sympathomimetics:
Ephedrine
Phenylephrine
47
**EPHEDRINE**
CLASSIFICATION & MOA
synthetic noncatecholamine sympathomimetic
DIRECTLY stimulates alpha and beta receptors
INDIRECTLY stimulates alpha and beta receptors by increased NE release
48
What are the clinical uses of ephedrine?
Increase BP
Decrease nausea (IM)
49
What is the PRINCIPAL reason that ephedrine increases BP?
increased contractility from Beta 1 activation
If beta blockers are on board, ephedrine will only cause vasoconstriction
50
How do the cardiovascular effects of ephedrine differ from those of epinephrine?
they're less intense and longer lasting
51
Phenylephrine mimics the effects of \_\_\_\_\_\_
norepinephrine
52
**PHENYLEPHRINE**
CLASSIFICATION & MOA
Synthetic noncatecholamine sympathomimetic
Mimcs the action of NE mostly at alpha 1 receptors
53
Which one raises the heart rate: ephedrine or phenylephrine?
Ephedrine
54
Does phenylephrine cause venoconstriction or vasoconstriction?
mostly venoconstriction
55
What happens to cardiac output when phenylephrine is given?
It decreases
Maybe from increased afterload, but more likely from reflex bradycardia from baroreceptor response to the sudden increase in BP
56
Name two beta two agonists
albuterol
terbutaline
57
What is the primary side effect of using beta 2 agonists?
Muscle tremors because of B2 receptors in skeletal muscle
58
**DIGOXIN**
CLASSIFICATION & MOA
Cardia Glycoside
Inhibit the Na-K sodium pump in the sarcolemma
Bind to the alpha subunit on the ATPase enzyme and stop it from transporting sodium ions out
The increased sodium ion concentration blocks the Na-Ca pump, so calcium builds up inside the cell
having more calcium inside the cell = stronger contraction
59
What electrolyte imbalance may cause dig toxicity?
Hypokalemia
Hypomagnesemia
Hypoxemia
60
How are potassium and digoxin related?
Potassium interferes with the binding of digitalis on cardiac muscle
61
Which phosphodiesterase inhibitors impact cardiac cells?
PDE III
62
In the myocardium, increased intracellular cAMP concentration results in:
stimulation of protein kinases that phosphorylate the sarcoplasmic reticulum → increased inward calcium current → increased intracellular calcium → increased contractility
63
In vascular smooth muscle, increased cAMP results in:
facilitates uptake of calcium by the sarcoplasmic reticulum → decreased intracellular calcium → vasodilation and smooth mm relaxation
64
Milrinone improves cardiac output by:
improving contractility (increased ca in myocardium)
Decreasing preload and afterload (reduced ca in vasculature)
65
What are the three invariable side effects of all alpha blockers?
Orthostatic hypotension (can't shunt blood)
Baroreceptor mediated reflex tachycardia
Impotence
66
**PHENTOLAMINE**
CLASSIFICATION & MOA
Non selective, competitive Alpha blocker
Alpha 1: peripheral vasodilation and decreased BP
Alpha 2: increased release of NE from the brain leads to increased HR and CO
67
What is the primary use for phentolamine?
acute hypertensive emergencies from pheochromocytoma manipulation or ANS hyperreflexia
68
**PHENOXYBENZAMINE**
CLASSIFICATION & MOA
Nonselective, irreversible alpha blocker
Blockade at both receptors, but primarily alpha 2
69
What is the primary use of phenoxybenzamine?
chronic alpha blockade for patients awaiting pheochromocytoma resection
70
Any drug ending in "-osin" belongs to what class?
Alpha blockers
71
Which beta blockers are preferred for patients with asthma and reactive airway disease?
Cardioselective beta blockers (beta 1 selective)
72
What are the effects of beta 2 blockade?
Bronchospasm
peripheral vascular insufficiency
73
Which beta blocker has the shortest half-life?
Esmolol
74
Which beta blocker has the longest half life?
Betaxolol and/or Nebivolol
75
How does propranolol impact clearance of LAs and opioids?
**LAs**: decrease clearance of amides because it decreases hepatic blood flow and inhibits metabolism
**Opioids**: decreases the first pass uptake of fentanyl. 2-4x as much drug enters the systemic circulation after injection
76
A patient with asthma is receiving metoprolol, but needs increasingly large doses. Eventually they develop wheezing. What should be given?
A Beta 2 agonist (terbutaline)
77
A patient with severe coronary artery disease should receive which beta blocker?
One that is as beta selective as possible BECAUSE beta 2 blockade will prevent coronary artery dilation
Atenolol is the current favorite for pre-treating cardiac patients undergoing noncardiac surgery
78
What does it mean if a beta blocker has intrinsic sympathomimetic activity?
It means that in addition to blocking certain beta receptors, it also agonizes others
79
If a patient cannot tolerate tachycardia due to intubation, which meds should be given?
Interestingly, lidocaine or fentanyl will reduce the BP response, but they will NOT stop the tachycardic response. Esmolol is a great choice for those patients.
80
How does esmolol interact with propofol?
It significantly decreases the plasma concentration of propofol required to prevent patient movement
81
How would giving a beta blocker impact blood sugar?
May cause hypoglycemia AND may mask the s/s of hypoglycemia
82
What's the difference between membrane stabilization and blockade?
Most beta blockers act by removing SNS innervation to the heart. BUT at high doses they will also hyperpolarize the cardiac resting membrane potential
83
Name two beta blockers that are partial beta agonists
pindolol
acebutolol
84
What is the initial drug if a beta blocker overdose is suspected?
Atropine
A beta selective agonist (like isoproterenol)
Glucagon
85
Why is glucagon given in beta blocker overdoses?
It increases intracellular cAMP independent of Beta adrenergic receptors
86
How do beta blockers impact metabolism?
Ordinarily when BG is low epinephrine is released. Beta blockers prevent it from binding in the liver and initiating glycogenolysis
87
How do beta blockers influence potassium levels?
Beta 2 receptors facilitate movement of potassium INTRACELLULARLY
beta blockade inhibits the uptake of potassium into skeletal muscles, increasing plasma levels
88
How do beta blockers and volatile anesthetics interact with one another?
They generally don't have much of an additive effect as far as myocardial depression goes
Sevo and Des have the least additive effect. Iso has a little.
89
How is the cardiovascular response to fentanyl altered by beta blockers?
It isn't!
Even with high doses, the CV response isn't altered
90
What impact do beta blockers have on the CNS?
fatigue and lethargy, but not well documented
91
Fetuses exposed to beta blockers are likely to be born with three symptoms:
bradycardia
hypotension
hypoglycemia
92
There are two combined alpha and beta receptor antagonists:
Labetalol
Carvedilol
93
Which receptors is labetalol selective for?
Selective Alpha 1
Nonselective Beta (1 and 2)
Alpha 2 is spared
94
Which calcium channel blockers are selective for the AV node?
Verapamil and Diltiazem
95
Which calcium channel blockers are selective for the arteriolar beds?
All the dihydropyridines:
Clevidipine, Nifedipine, Nicardipine, Nimodipine, Amlodipine
96
What are common side effects of calcium channel blockers?
hypotension
peripheral edema
flushing
headache
97
All calcium channel blockers bind to the same subunit of slow calcium channels:
the alpha 1 subunit
98
Which calcium channel blockers are effective in treating coronary artery spasm?
All of them
99
Which calcium channel blockers exert negative inotropic effects?
All of them, but verapamil and diltiazem are the most significant
100
Which patients should not receive verapamil?
Patients in heart failure or who have any kind of heart block
101
Verapamil may precipitate ventricular dysrhythmias in patients with what disease?
WPW
102
What is special about nimodipine?
It favors cerebral vessels
103
Are the dihydropyridines vasodilators or venodilators?
Almost exclusively arterial
104
What should you be on the lookout for anytime you begin a dihydropyridine?
reflex tachycardia
You're decreasing BP but not blunting the heart
105
Why is nifedipine used as a tocolytic?
It prevents calcium from moving into the uterine cells, which decreases contractile strength
106
What is special about nicardipine?
It can be given IV. All the other dihydropyridines have to be given PO.
107
How do calcium channel blockers impact NMBAs?
They potentiate the effects of ALL NMBAs
108
Which calcium channel blockers have a local anesthetic effect?
verapamil and dilt
109
Do calcium channel blockers have effects at the NMJ?
Not in healthy patients, but in patients with muscular dystrophy they seem to cause pretty profound skeletal muscle weakness that isn't consistent with just decreased neurotransmitter release
110
How do calcium channel blockers impact potassium movement across the cell membrane?
the slow the inward movement of potassium, which increases the risk for hyperkalemia
