Adrenergic Stimulants Flashcards
1
Q
Formation of adrenergic molecules
A
tyrosine –> L-Dopa –> Dopamine (ends here orrr) –> NE –> E
2
Q
Where is NE converted to E
A
adrenal medulla
3
Q
Rate limiting step and what is it blocked by
A
Tyrosin –> L-dopa;
blocked by metyrosine
4
Q
Increase release of NE at presynaptic terminal
A
Tyramine and amphetamine (only have effect if noradrenergic innervation is intact)
5
Q
What blocks reuptake of NE
A
antidepressant and cocaine
6
Q
metabolize NE
A
monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT)
7
Q
MAO
A
on outer surface of mitochondria, breaks down NE in presynatptic terminal
8
Q
COMT
A
found throughout body, especially in liver, breaks down circulating NE and EPI
9
Q
How to measure NE and EPI concentrations
A
measure VMA (mandelic acid) and HVA (homovanillic acid) in 24 hour urine sample
10
Q
Alpha receptor order
A
EPI > NE»_space; Isoproterenol
11
Q
beta-1 order
A
Iso > EPI = NE
12
Q
Beta-2 order
A
Iso > EPI»_space; NE
13
Q
Beta-3 Order
A
Iso = NE > EPI
14
Q
alpha 1 agonist
A
phenylephrine
15
Q
alpha 2 agonist
A
clonidine
16
Q
Clonidine actions
A
aggregation of platelets
some smooth muscle contraction
decrease insulin secretion
17
Q
NE has little effect on what receptors
A
B2
18
Q
What has a greater effect on beta3 receptors, NE or EPI?
A
NE
19
Q
Beta1 agonst
A
Dobutamine
20
Q
Dobutamine effects
A
increase contraction and HR
increase AV conduction
Increase renin secretion
21
Q
Beta 2 receptor agonist
A
ALbuterol
22
Q
Albuterol effects
A
Relax respiratory, uterine, GI smooth muscle
Relax blood vessels to skeletal muscle
promote potassium uptake in skeletal muscle
increase glycogenolysis
23
Q
Beta-3 receptor effects
A
increase lipolysis
24
Q
DA receptor location
A
brain, renal and splanchnic vasculature
25
D1
stimulate adenylyl cyclase and causes dilation of renal blood vessels (increasing RBF)
26
D2
inhibits adenylyl cyclase, open potassium channels, and decrease Ca influx, which generally inhibits release of transmitters from nerve terminals
27
Atherosclerosis and alpha 1 receptors
baroreceptor response may be impaired, so alpha agonist effect on BP will be magnified
28
Norepinephrine effects what receptors
alpha stimulation causes vasocontriction, increases BP
| B1 stimulation increases HR, overcome by baroreceptor reflex
29
Norepinephrine facts
must be injected
increase PR, increased BP, PP unchanged
Dec. blood flow to kidney, spleen, liver
HR increases, reversed by baroreceptor reflex
CO unchanged or decreased
Atropine prior to NE will block vagal reflex, HR will increase
Short action, vasoconstriction at infusion site, used to reverse hypotension; necrosis if poor blood flow
30
NE clinical use
RARE; hypotensive crisis!
31
Epinephrine receptors
alpha: vasocontriction, initially increases diastolic pressure
Beta1- increases HR, contraciton (increased PP)
beta 2- dilate blood vessels to skeletal muscle, decrease diastolic
PP increases MAP doesn't change much
CO and O2 consumption increase
Beta-2 more sensitive to EPI than alpha!!!
32
Dose dependence of epinephrine
low dose: B2 (vasodilation of skeletal muscle- dec. diastolic)
High dose: alpha receptors (vasoconstriciton, BP increases - inc. diastolic)
33
Other effects of epinephrine
```
increased glycogenolysis (blood sugar increases)
increased lipolysis
dec. insulin secretion (a2)
renin increases
bronchodilation
```
34
Difference between NE and EPI receptor stimulation
NE does not stimulate B2 (bronchodilation, dilation to skeletal mm. vessels)
35
alpha block + epi
take away vasoconstriction, now only have vasodilation -- no BP increase anymore, diastolic decreases
36
Beta block + epi
no increased contractility or HR increase; no more vasodilation to even out BP, so you see a LARGE increase in BP; aortic flow decreases (w/ higher diastolic)
37
Used of epinephrine
anaphylactic shock (restore BP, decrease bronchospasm, decrease congestion and angioedema, reverse CV collapse)
Emergency tx for cardiac arrest and complete heart block
vasoconstrictor used to decrease diffusion of injected drugs such as local anesthetics
glaucoma- dec. production, increase removal
bronchodilation (emergency tx of asthma-rarely)
38
SE of EPI
tremor, throbbing h/a, increased BP, tachycardia; angina in patients with CAD (increased O2 consumption and increased cardiac work);
most potent vasopressor available: low dose- vasodilation, high dose - alpha, vasoconstriction
Injection at high dose could cause extreme inc. in BP and cerebral hemorrhage or ventricular arrhythmias
39
Contraindicationss of EPI
beta-blockers (severe HTN!)
40
Where is ephedra found
herbal supplements and weigh loss preparations
41
What is ephedra
stimulates alpha and Beta, and increases NE release
effects similar to EPI
CNS stimulant, Inc. HR and BP; bronchodilation; taken off market due to death from HTN
42
phenylpropanolamine
similar to ephedra; in OTC decongestants and weight loss; taken off market due to hemorrhagic stroke in women
43
Catecholamines
NE
EPI
Isoproterenol
44
Alpha Agonists
Phenylephrine (a1)
pseduoephedrine
oxymetazoline
midodrine
45
Phenylephrine
vasoconstriction inc. PR, BP increases - reflex slows HR
46
Use of phenylephrine
Hypotensive emergency
decongestant (rebound effect)
mydriasis (eye exam)
47
Phenylephrine receptor
selective for alpha-1
48
Side effect of phenylephrine
rebound congestion
HTN (caution w/ hypertensive patients)
mydriasis
49
Pseudoephedrine (Sudafed)
```
alpha agonist similar to phenylephrine
OTC decongestant
caution in HTN patients
precursor for methampheatamine
more effective orally than phenylephrine
```
50
Precursor for meth
pseudoephedrine
51
Use of pseudoephedrine
OTC decongestant
52
Oxymetazoline (Afrin)
direct alpha agonist
vasoconstriction, used on nasal mucosa and in eye
nasal decongestatant (rebound effect)
also works on ALPHA-2 (hypotension if a large quantity)
53
oxymetazoline
topically as nasal spray (rebound effect) - hypotension in HIGH doses (alpha-2)
54
Decrease redness in eye via vasoconstriction
tetrahydrozoline, naphazoline
55
Contraindications for tetrahydrozline, naphazoline
narrow angle glaucoma and HTN
56
Used to treat symptomatic orthostatic hypotension
midodrine
57
Alpha 2 agonists
```
CLONIDINE
methyldopa
apraclonidine
dexmedetomidine
tizanidine
```
58
Clonidine
selectve a2 agonist in brain (CNS!)
decreases release of NE and overall symapthetic output
oral or transdermal patch
59
Effect of clonidine
decrease BP
60
Clonidine use
hypertension
reduce cravity/withdrawal symptoms for opiods and alcoholics
decrease hot flashes in menopause
pre-anesthetic med to cause sedation and dry secretions
61
SE of clonidine
dry mouth, sedation, sexual dysfunction
avoid getting patch too hot - massive release of clonidine leading to hypotension
HTN may occur if patch is withdrawn abruptly
62
Methyldopa (also: guanabenz, guanfacine)
alpha 2 agonist similar to clonidine
63
Apraclonidine (& brimonidine)
alpha 2 agonist; used in EYE to decrease intraocular pressure by reducing formation of aqueous humor thru a2 receptor mediated vasoconstriction
64
Dexmedetomidine
selective a2-adrenoceptor agonist w/ centrally mediated sympatholytic, sedative and analgesic effects
65
Tizanidine
a2 agonist w/ less effect on BP than clonidine; REDUCED MUSCLE SPASTICITY
66
Isoproterenol
B1 and B2; vasodilation causes decreased BP with reflex increased HR;
67
Use of isoproterenol
used to be used for asthma
68
SE of isoproterenol
tachycardia, palpitations, arrhythmias
69
Dobutamine
B1 selective; increased CO and contractility
70
Use of dobutamine
cardiac stress test
| increase CO in cardiogenic shock and CHF
71
SE of dobutamine
increased HR and HTN, especially if already HTN
72
Terbutaline, albuterol
B2 selective; bronchodilation; used to treat asthma
73
Mirabegron
B3 selective; used for OAB
SE: HTN, sinus tachy, h/a, dizziness
74
Dopamine
D1 selective; high dose effects almost all receptors (b1, a1)
SE: increased HR, vasoconstriction, n/v; high dose: similar to EPI
75
Use for dopamine
cardiac shock
76
Fenoldopam
more D1 selective; dilates renal vascular beds
77
Fenoldopam use
decrease BP in severe HTN
78
Amphetamine
increases release of NE and DA; CNS stimulant (euphoria, alertness, decreased need to sleep and eat)
79
SE of amphetamine
psychosis, tachycardia, HTN, tremors
80
Toxicity of amphetamine
cerebral hemorrhage, convulsions, coma
81
Metahmphetamine
more central effects, less peripheral; drug of abuse
82
Methylphenidate (ritalin)
used to treat ADHD (decreases hyperactivity)
83
Cocaine MOA
prevents reuptake of NE and DA in nerve terminals
84
Cocains effects
similar to amphetamine, but shorter acting and more intense; smoked (crack) to intensify effect; highly addicting;
85
SE of cocaine
HTN and stroke in healthy individuals; tachycardia and arrhythmias and MI; psycosis in long term use
86
Clinical use of cocaine
vasoconstrictor: nasopharyngeal surgery to decrease blood flow and produce local anesthesia
87
Tyramine
increases release of NE and DA; forms false neurotransmitter (octopamine); tachyphylaxis develops
88
Contraindication for tyramine
MAOI inhibitos (MAOI hydrolyzes tyramine) -- can lead to hypertensive crisis
