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Sympathomimetics Flashcards

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1
Q

What complication can arise with phase 4 spontaneous depolarization with Epinephrine?

A

Cardiac arrhythmia’s

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2
Q

A mild decrease in DBP with Epi is from…

A

Beta 2 stimulation of skeletal muscle vasculature

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3
Q

Is there a large or small change in MAP with Epi?

A

Small

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4
Q

What happens with repeated doses of Epi?

A

Produces same results (there is no tachyphylaxis with Epi)

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5
Q

What hemodynamics does Epi increase with alpha 1 sitmulation?

A

SVR, afterload, venous return, SV, CO

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6
Q

What hemodynamics does Epi increase with beta 1 stimulation?

A

HR, CO, contractility, oxygen consumption

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7
Q

What is secreted with renal stimulation of Epi?

A

Renin (increases BP)

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8
Q

Vasoconstriction/dilation occurs in what vessels with Epi?

A

Vasoconstriction: all vessels besides coronary (dilation)

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9
Q

Administration of what class of drugs can alter Epi’s effects?

A

Alpha or beta antagonists

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10
Q

Supratherapeutic doses of Epi leads to?

A

HTN, acute HF, pulmonary edema, myocardial ischemia, arrythmias.

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11
Q

Stimulation of Beta 2 recepotors with Epi results in what?

A

Bronchodilation and decreased bronchoconstriction (seen with increased airway resistance diseases and anaphylaxis)

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12
Q

Beta 2 adrenergic blockade results in what pulmonary issue?

A

Bronchoconstriction

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13
Q

Epinephrine has the most significant effect on metabolism of…

A

All catecholamines

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14
Q

Beta 2 stimulation of epi results in what?

A

Bronchodilation and increased liver glycogenolysis and adipose tissue lipolysis (breaks down fat and glycogen)

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15
Q

Alpha 1 stimulation with Epi results in what endocrine effect?

A

Inhibition of insulin release

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16
Q

Infusions of Epi increase concentrations of?

A

Glucose, cholesterol, phospholipids, and low density lipoproteins

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17
Q

What is the most likely cause of perioperative hyperglycemia?

A

Endogenous release of Epi - increased glycogenolysis and inhibition of insulin release

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18
Q

Epinephrine can also ______ peripheral glucose uptake.

A

inhibit

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19
Q

Increased plasma concentrations of _____ may reflect epinephrine induced glycogenolysis in skeletal muscles.

A

lactate

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20
Q

With Epi, hyperlactemia is usually what?

A

transient

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21
Q

What can arise with Epinephrine induced hypokalemia?

A

Cardiac dysrhythmias, which can stimulate SNS. The liver can offset the decrease in extracellular concentration of K+ produced by entrance into the skeletal muscle.

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22
Q

Stimulation of what receptor leads to hypokalemia?

A

Beta 2 (Epi)

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23
Q

Stress release of Epi during induction can lead to what?

A

Hypokalemia (goes intracellular)

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24
Q

What drug may prevent hypokalemia?

A

Propranolol (beta 1 and 2 antagonist)

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25
What drug can lead to hypokalemia?
Atenolol (cardioselective beta 1 antagonist)
26
Contraction of radial muscle in eyes produce what effect? What receptor does this occur on?
Mydriasis; alpha 1
27
With Epi, contraction of the orbital muscles can produce what?
exopthalmos (most likely related to alpha receptor stimulation)
28
What drugs produce relaxation of the GI smooth muscle?
Alpha 2 stimulators
29
Activation of alpha receptors with Epi does what to the urinary area?
constriction of sphincters of the bladder and trigone of bladder (signals brain to empty)
30
Hepatosplanchnic and renal vasoconstriction occurs with which drug?
Epi
31
What does Epi do to the blood?
Increases coagulation and can induce platelet aggregation with increase in factor V activity
32
Where is Epi stored and released?
Adrenal Medulla
33
Where is Norepi stored and released?
Postganglionic sympathetic nerve endings - it will be released with SNS stimulation
34
What is the immediate precursor to Epi?
Norepi
35
Norepi stimulates what receptors?
Alpha 1 and Beta 1 - minimal effect on Beta 2!!
36
Vascular capacitance (with Norepi) is equal to what?
The change in volume divided by the change in pressure - Norepi does not utilize vascular capacitance to increase BP (it uses increase in afterload).
37
Will HR rise with Norepi?
Not much - baroreceptor mediated responses will decrease HR due to sensing increased vasoconstriction - Epi has more of a chronotropic effect than Norepi.
38
Metabolic effects are not commonly seen with what drug?
Norepi - metabolic effects are more common with Epi. Hyperglycemia is unlikely to occur with Norepi
39
With Norepi, intense vasoconstriction occurs in....
skeletal muscle, liver, kidneys, and vascular beds in the skin
40
What issue can occur with intense vasoconstriction with Norepi?
peripheral vasoconstriction which can lead to metabolic acidosis
41
Continuous infusion of Norepi should be what dose and for what disorder?
2-16 mcg/min; refractory hypotension
42
Norepi/phenylephrine needs to be given in a large CVL to prevent?
Extravasation - may need to give phentolamine 5-15 mg IV
43
What prevents uptake of Norepi?
TCA's and cocaine
44
Where is Norepi stored?
adrenergic nerve endings - will be re-uptake here to be used for future use.
45
How much Norepi is metabolized? How is it metabolized?
Little; MOA and COMT
46
Norepi is the first line treatment in what?
Refractory hypotension with severe sepsis - decrease in blood flow to peripheral and increased blood flow to sphlanchnic area may increase UOP.
47
What kind of surgical patients can Norepi be used in?
CABG with low SVR
48
What is the biggest concern with increased pulmonary artery pressure increase with Norepi?
RV failure (alpha 1 stimulation causes vasoconstriction)
49
Major concern with Norepi?
Organ failure - especially renal (can cause oliguria with severe hypoperfusion)
50
What needs to be given with Norepi to increase perfusion pressure of renal blood flow?
volume
51
What kind of drug is ephedrine?
Indirect synthetic non-catecholamine - stimulates alpha and beta adrenergic receptors
52
What is responsible for the prolong effects of ephedrine?
its slow inactivation and excretion
53
Effects of ephedrine
Crosses BBB, no hyperglycemia present, and mydriasis can occur
54
Typical dose of ephedrine
5-10 mg
55
Why is ephedrine commonly used?
to increase systemic BP in the presence of sympathetic nervous system blockade produced by regional anesthesia or hypotension due to inhaled or injected anesthesia
56
Why phenylephrine over ephedrine in pregnant patients?
Ephedrine can cause acidosis whereas phenylephrine will increase pH of fetus
57
Onset of ephedrine compared to epi?
ephedrine onset is slower than epi's onset
58
What is the antiemetic effect dose of ephedrine?
0.5 mg/kg (similar effects as droperidol at this dose)
59
Ephedrine resembles epi in its CV effects except..
Ephedrine's effect on BP is less intense but lasts 10x than Epi
60
SVR is minimally altered with ephedrine due to what?
vasoconstriction in some vascular beds is offset by vasodilation in others (beta 2 stimulation)
61
What is the principle mechanism for CV effects produced by ephedrine?
Increased contractility (inotropic effect) by beta 1 stimulation
62
In the presence of beta blockade while giving Ephedrine, what response will you likely see?
Effects resembling alpha adrenergic stimulation
63
Does tachyphlaxis occur with ephedrine?
yes - second dose does not produce as intense of an effect as the first dose
64
What type of drug is phenylephrine?
Direct synthetic non-catecholamine
65
Phenylephrine mimics which drug?
Norepi - but it lasts longer and stimulates alpha 1 principally
66
Is phenylephrine a direct or indirect acting drug?
More direct -minimal indirect effect on release of norepi does occur
67
What receptors does phenylephrine work on?
Primarily alpha - minimal beta effects. The dose to stimulate alpha 1 is far less than that to stimulate alpha 2 a1 > a2
68
What will determine whether to use ephedrine or phenylephrine?
HR
69
Typical dose of phenylephrine?
50-200 mcg IV bolus - primarily venous constriction rather than arterial constriction Typical dose is 50-100 mcg IV infusion: 20-200 mcg/min
70
What kind of patients is phenylephrine good for?
CAD and aortic stenosis - increases coronary perfusion without chronotropic effects like most other sympathomimetics
71
What is the typical continuous dose of phenylephrine to maintain adequate BP during surgery?
20-100 mcg/min
72
In the presence of SVT, what sympathomimetic can help?
Phenylephrine due to its vagal effects and has minimal or zero beta effects. DO NOT GIVE EPI, NOREPI, or EPHEDRINE!
73
Where does phenylephrine decrease blood flow?
renal, splanchnic, and cutaneous
74
Where does phenylephrine increase blood flow?
coronary arteries and pulmonary arteries
75
Why not give potassium with phenylephrine?
vasoconstriction wont allow potassium into cells = hyperkalemia
76
Signs of phenylephrine overdose and what is the treatment?
Hypertension, tachycardia, baroreceptor mediated bradycardia - give phentolamine
77
Why does phentolamine work with phenylephrine toxicity?
Its an alpha 1 antagonist (phenylephrine is alpha 1 agonist)
78
Phenylephrine is contraindicated with what? This is on test!
Beta 1 antagonists (decreases CO) - phenylephrine will further decrease CO by increasing SVR
79
What are some tissues that phosphodiesterase enzymes exist?
cardiac muscle, vascular smooth muscle, platelets, liver, lungs
80
How often do PDI's cause arrythmias?
rarely
81
What do inodilators do?
Decrease preload and afterload
82
What is unique about PDI and contractility and beta blockade?
They act independently of beta blockade and will continue to increase contractility
83
What other drugs can be given with PDI's to increase contractility without major issues?
Digitalis
84
Effects of amrinone?
Increased contractility with vasodilation (increased CO and decreased LVEDP)
85
Amrinone can increase CO by what mechanisms?
Vasodilation or contractility
86
What is the half-life of amrinone?
1-2 minutes but elimination half-time is 2.6-4.1 hours
87
What is the typical dosing of amrinone?
Loading: 0.5-1.5 mg/kg (push slow to avoid hypotension) Continuous: 2-10 mcg/kg/min Max daily dose: 10 mg/kg
88
Major side effect with amrinone?
Hypotension - may need vasopressor given with it
89
Why did milrinone replace amrinone?
Milrinone is 30x more potent with less side effects
90
Typical milrinone dosing?
Bolus: 50 mcg/kg over 10 minutes followed by infusion Continuous infusion: 0.375 -0.75 mcg/kg/min Max daily dose: 1.3 mg/kg/day
91
How protein bound is milrinone?
70% - sticks around!
92
Elimination half-time of milrinone?
2.7 hours and 80% excreted unchanged by urine
93
What to do in renal patients when using milrinone?
Decrease dose
94
Unlike dobutamine, milrinone rarely causes what?
tachyarrythmias
95
Why dobutamine over milrinone?
hypotension or renal dysfunction
96
Major side effects with milrinone
hypotension, increase morbidity and mortality in CHF (not FDA approved for heart failure), and rapid administration may cause arrhythmia's
97
Major electrophysiological effect of milrinone?
atrioventricular nodal conduction
98
What arrythmias have been reported with milrinone?
ventricular and supraventricular
99
Long-term IV infusion of milrinone causes what?
platelet aggregation
100
What receptors does Norepi work on?
Alpha 1 and Beta 1 (minimal beta 2)
101
How is norepi metabolized?
Mainly reuptake into post ganglion for future use but can be metabolized by MOA and COMT
102
Where does blood flow go with norepi use?
Vasoconstriction causes more blood flow to sphlanchnic region and may see an increase in UOP
103
If beta blockers were given prior to ephedrine administration, what happens?
Ephedrine will stimulate alpha receptors more greatly than beta

Pharmacology (5 decks)

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