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[Ther 201] 2nd Exam Transes > Adrenergic Agents and Blockers (Maria Concepcion Sison, MD) > Flashcards

Adrenergic Agents and Blockers (Maria Concepcion Sison, MD) Flashcards

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1
Q

Adrenergic agents are also known as what?

A

Sympathomimetics

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2
Q

Define: Sympathomimetics

A

Mimic epinephrine and norepinephrine and activate the sympathetic nervous system

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3
Q

Where is norepinephrine released from? Epinephrine?

A

Nerve terminals; adrenal glands

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4
Q

Where do the central components of the sympathetic nervous system reside?

A

Hypothalamus, brain stem and spinal cord

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5
Q

Describe the structure of the sympathetic nervous system

A

Originate from thoracic and lumbar areas

Preganglionic axons synapse on neurons close to spinal cord

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6
Q

T/F: The adrenal medulla is a modified ganglion innervated by sympathetic postganglionic axons.

A

False.

Preganglionic!

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7
Q

What drug inhibits formation of tyrosine hydroxylase?

A

Metyrosine

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8
Q

What drug inhibits sequestration of dopamine in vesicles?

A

Reserpine

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9
Q

What drug inhibits vesicular exocytosis into the pre-synaptic cleft?

A

Guanethidine

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10
Q

What drugs prevent re-uptake of norepinephrine?

A

Cocaine and TCA

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11
Q

What type of receptor predominates in the pre-synaptic membrane?

A

Alpha-2

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12
Q

What does VMAT stand for?

A

Vesicular monoamine transporter

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13
Q

What is another name for adrenoceptor antagonists?

A

Sympatholytics

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14
Q

What processes do indirect adrenergic agonists affect?

A

Synthesis, storage and release

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15
Q

What are the types of adrenoceptors?

A 
Alpha-1 (A, B, D)
Alpha-2 (A, B, C)
Beta-1
Beta-2
Beta-3
Dopamine (D1, D2, D3, D4, D5)
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16
Q

Where are alpha-1 receptors located?

A

Postsynaptic effector cells, heart, smooth muscles and glands

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17
Q

Where are alpha-2 receptors located?

A

Presynaptic adrenergic nerve terminals, platelets, lipocytes, smooth muscle and lower brainstem region (medulla)

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18
Q

What is the mechanism of the alpha-1 receptor?

A

Gq activates PLC. There is formation of IP3 and DAG and increased intracellular Ca2+.

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19
Q

What is the mechanism of the alpha-2 receptor?

A

Gi causes decreased cAMP due to inhibition of adenylyl cyclase

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20
Q

T/F: Alpha-1 is clinically significant in constriction and dilatation of blood vessels.

A

True

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21
Q

T/F: Alpha-1 agonists behave like blockers.

A

False

Alpha-2 agonists!

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22
Q

T/F: Alpha-2 agonists are unique because they are also found in the presynaptic membrane.

A

True

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23
Q

Where are beta-1 receptors located?

A

Postsynaptic effector cells in heart, adipocytes, brain, presynaptic adrenergic and cholinergic nerve terminals, and JGC

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24
Q

Where are beta-2 receptors located?

A

Postsynaptic effector cells in smooth muscle (lungs, vessels and GIT) and cardiac muscle

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25
Where are beta-3 receptors located?
Postsynaptic effector cells in lipocytes
26
What is the mechanism of the beta adrenergic receptors?
Gs protein stimulates adenylyl cyclase to produce more cAMP
27
T/F: Alpha-1 and beta-2 have opposite effects.
True
28
What are the most important dopamine receptors?
D1 and D2
29
Where are the dopamine receptors found?
CNS Brain Splanchnic & renal vasculature
30
Which dopamine receptors increase cAMP? decrease cAMP?
D1 & D5 - increase cAMP (Gs) | D2 to D4 - decrease cAMP (Gi)
31
Where is D1 found?
Smooth muscles (stimulation increases cAMP)
32
Where is D2 found?
Nerve endings
33
What is the basis for adrenoreceptor classification?
Structure-activity relationships
34
What is notable in the chemical structure of epinephrine?
It has a methyl group.
35
What is notable in the chemical structure of norepinephrine?
It has no methyl group.
36
What is notable in the chemical structure of isoproterenol?
It has a isopropyl group.
37
What is the graph profile of the beta-1 receptor?
Iso > E >/= NE (Effect on Force of Contraction)
38
What is the graph profile of the beta-2 receptor?
Iso > E >> NE (Effect on Bronchodilation)
39
What is the action of an adrenergic agonist?
Inhibits the degradation of cAMP
40
What is the graph profile of the alpha-1 receptor?
E >/= NE >> ISO (Effect on Bronchoconstriction)
41
Response of any cell or organ to sympathomimetic depends on what?
Density and proportion of adrenergic receptors
42
What are the potential actions of the adrenergic receptors?
1. Peripheral excitation 2. Peripheral inhibition 3. Cardiac excitation 4. Metabolic action 5. Endocrine action 6. CNS action 7. Prejunctional action
43
What are the tissue distribution of and actions mediated by the alpha-1 receptor?
``` Vascular smooth muscle - contraction Pupillary dilator muscle - contraction Pilomotor smooth muscle - erection Prostate - contraction Heart - inc. force of contraction ```
44
What are the tissue distribution of and actions mediated by the alpha-2 receptor?
Postsynaptic CNS adrenoceptors - decreased blood pressure Platelets - aggregation Adrenergic & cholinergic nerve terminals - inhibition of transmitter release Vascular smooth muscle - contraction Fat cells - inhibition of lipolysis
45
What are the tissue distribution of and actions mediated by the beta-2 receptor?
Respiratory, uterine and vascular smooth muscle - relaxation Skeletal muscle - K+ uptake Liver - glycogenolysis Uterine smooth muscle - relaxation
46
What are the tissue distribution of and actions mediated by the beta-1 receptor?
Heart - increased force & rate of contraction | JG Cells - increased renin release
47
What are the tissue distribution of and actions mediated by the beta-3 receptor?
Fat cells - lipolysis
48
What are the tissue distribution of and actions mediated by the D1 receptor?
Smooth muscle - dilates renal blood vessels
49
What are the tissue distribution of and actions mediated by the D2 receptor?
Nerve endings - modulates transmitter release
50
T/F: D1 can improve urine output.
True
51
Enumerate the direct-acting selective adrenergic agonists and the receptors they target.
``` Phenylephrine - alpha 1 Clonidine - alpha 2 Dolbutamine - beta 1 Albuterol/terbutaline - beta 2 D1 - Fenoldopam D2 - Bromocriptine ```
52
Enumerate the direct-acting non-selective adrenergic agonists and the receptors they target.
Oxymetazoline - alpha 1 & 2 Isoproterenol - beta 1 & 2 Epinephrine - alpha 1 & 2, beta 1 & 2 Norepinephrine - alpha 1 & 2, beta 1
53
Enumerate the indirect-acting releasing agents
Amphetamine | Tyramine
54
Enumerate the indirect-acting uptake inhibitors
Cocaine | Tricyclic antidepressants
55
Enumerate the mixed-acting adrenergic agonists and the receptors they target.
Ephedrine - alpha 1 & 2, beta 1 & 2 + releasing agent | Dopamine - D1 & 2, alpha and beta + releasing agent
56
T/F: Receptor specificity/selectivity is absolute.
False It is relative NOT absolute. e.g. beta-1 agonist can bind with beta-2 receptor if it is given at a high enough concentration.
57
Describe pheochromocytoma
1. Increased production of NE | 2. Request for urine vancodilic acid
58
Describe phenylethylamine
1. Selective alpha-1 agonist w/ hydroxyl group at C3 2. Found in chocolates 3. Increases dopamine levels at mesolimbic pleasure centres
59
Describe tyramine
1. Monoamine compound derived from tyrosine | 2. Releases monoamines such as dopamine, NE and E
60
What have the highest affinity to beta receptors?
Catecholamines
61
What does increasing the size of the alkyl group attached to the amino group do?
Increases affinity for beta receptors and decreases affinity for alpha receptors
62
T/F: All adrenergic compounds are catecholamines.
False
63
T/F: Maximal alpha and beta receptor binding is found in catecholamines.
True
64
Why is phenylephrine given parenterally?
It is not a catecholamine. It only has 1 OH group.
65
Describe phenylephrine
1. Arterial vasoconstriciton 2. Nasal decongestant 3. Mydriatic
66
Decreased substitution causes?
1. Increased bioavailability (spared from COMT inactivation in gut and liver) 2. Increased distribution to CNS (ephedrine & amphetamine)
67
T/F: Phenylisopropanols are given intravenously.
True
68
T/F: NE cannot be given subcutaneously.
False
69
What is the effect of substitution at the alpha carbon?
1. Block oxidation by MAO 2. Prolong action 3. Displace catecholamines from storage sites
70
What is the effect of substitution at the beta carbon?
1. Direct acting agonists usually have this. | 2. Important for storage of sympathomimetic amines
71
Enumerate the alpha 1 agonists
Phenylephrine Midodrine Methoxamine
72
Enumerate the alpha 2 agonists
Clonidine Methylnorepinephrine Methyldopa
73
Enumerate the mixed alpha and beta agonists
Epinephrine | Norepinephrine
74
Enumerate the beta 1 agonists
Dobutamine
75
Enumerate the beta 2 agonists
Terbutaline | Albuterol
76
Enumerate the dopamine agonists
``` Dopamine Fenoldopam (D1 over D2) ```
77
T/F: Isoproterenol possesses the same affinity for both beta 1 and 2 receptors.
True
78
Describe dopamine
1. Vasoactive, direct and indirect agonist 2. Precursor to NE 3. Acts indirectly by causing norepinephrine release 4. Binds to beta 1 at intermediate concentrations 5. Binds to alpha 1 at high concentrations
79
What are the effects of a beta 1 agonist on the CVS?
1. Positive chronotropic and inotropic agent 2. Accelerated relaxation 3. Increased AV conduction and decreased refractory period 4. Congestive heart failure and cardiogenic shock
80
What are the effects of dobutamine?
+ isomer - beta 1 agonist, alpha 1 antagonist, vasodilation | - isomer - alpha 1 agonist, beta 1 antagonist, vasoconstriction
81
What are the effects of a beta 2 agonist on the CVS?
1. Vasodilation | 2. Reflex response in heart rate
82
What are the effects of an alpha 1 agonist on the CVS?
1. Constriction of smooth muscles of resistance vessels 2. Reflex baroreceptor vagal discharge 3. Anaphylactic shock (high dose NE) 4. Bradcardia 5. Septic shock (epinephrine) 6. Congestive heart failure (high dose dopamine)
83
What are the effects of an alpha 2 agonist on the CVS?
1. Reduction in BP (decreased NE & medulla activity) | 2. Vasodilation
84
How does an alpha 2 agonist reduce blood pressure?
1. Activation of postsynaptic alpha 2 receptors dampening activity of vasomotor neurons in the medulla oblongata 2. Activation of presynaptic alpha 2 receptors decreasing release of NE.
85
Summarize the CVS effects of sympathomimetics on heart rate
Isoproterenol - increase (dec. TPR) Norephephrine - decrease (inc. TPR) Low dose epinephrine - increase (dec. TPR) High dose epinephrine - decrease (inc. TPR)
86
What is the effect of a beta 2 agonist on the respiratory tract?
Bronchodilation
87
What are the effects of an alpha 1 agonist on the respiratory tract?
1. Vasoconstriction of blood vessels of URT | 2. Nasal decongestion
88
Why shouldn't alpha 1 agonists be taken by hypertensive patients?
It may aggravate the hypertension.
89
What are the effects of an alpha 2 agonist on the gastrointestinal tract?
1. Reduce release of ACh (decrease BP) 2. Enhance salt and water reabsorption 3. Treatment of diarrhoea in diabetics with autonomic neuropathy (clonidine)
90
What are the effects of a beta 2 agonist on the genitourinary tract?
1. Relax uterine smooth muscle | 2. Relax bladder wall
91
What are the effects of an alpha 1 agonist on the genitourinary tract?
1. Constriction of the base | 2. Hypertension
92
What are the effects of beta agonists on metabolism?
1. Increase glycogenolysis 2. Increase lipolysis 3. Increase insulin (beta 2) and renin (beta 1) secretion 4. Promotes potassium re-uptake
93
What are the effects of an alpha 2 agonist on metabolism?
1. Decreases release of NE 2. Decreases insulin and renin action 3. Inhibition of lipolysis
94
What is the effect of a beta receptor agonist on the eye?
Relaxation of ciliary muscle with decrease in accommodation
95
What are the effects of an alpha receptor agonist on the eye?
1. Mydriasis | 2. Decreases intraocular pressure
96
Phenylephrine causes mydriasis without what?
Cyclopegia
97
What is the effect of catecholamines at a high infusion rate on the CNS?
Feeling of impending disaster
98
What are the effects of non-catecholamines on the CNS?
``` Mild improvement in alertness Elevation of mood Insomnia Euphoria Anorexia ```
99
What is the mechanism of action of amphetamine?
Displaces norepinephrine from vesicles into the cytosol and blocks MAO This results in hyperactivity and narcolepsy in children!
100
Compare dobutamine and isoproterenol
Dobutamine is more inotropic than chronotropic.
101
Describe the toxicity of pressor agents
Marked increase in BP Cardiac ischemia and failure Heart failure
102
Describe the toxicity of beta agonists
Sinus tachycardia | Ventricular arrythmias
103
Describe the toxicity of amphetamines
Restlessness Tremors Anxiety Paranoid state
104
Describe the toxicity of cocaine
Convulsions Hemorrhage Arrythmias
105
Methyldopa is the prodrug of?
Alpha-methylnorepinephrine
106
Describe: Clonidine
1. Tested as topical nasal decongestant 2. Anti-hypertensive effect 3. Activates alpha 2 receptors in lower brainstem
107
Enumerate the selective alpha 1 antagonists
Prazosin Terazosin Doxazosin
108
Give a selective alpha 2 antagonist
Yohimbine
109
Enumerate the non-selective alpha antagonists
Phenoxybenzamine (irreversible antagonist) | Phentolamine (reversible antagonist)
110
What are the effects of an alpha antagonist on the CVS?
1. Relaxes smooth muscle 2. Decreases PVR, venous return and blood pressure 3. Orthostatic hypotension as a side effect 4. Blockade of RAS
111
T/F: Phenoxybenzamine has a higher affinity for alpha 1 than alpha 2 receptors.
True
112
What is the first selective alpha 1 antagonist?
Prazosin
113
Why should alpha receptor blockade come before beta receptor blockade?
This prevents an increase in BP from vasoconstriction.
114
T/F: A low dose of epinephrine causes it to bind to beta receptors.
True
115
Give an example of a non-selective beta antagonist
Propanolol
116
Enumerate the selective beta 1 antagonists
``` Betaxolol Esmolol Acebutolol (paritla agonist) Atenolol Metoprolol ``` BEAM!
117
Give an example of a selective beta 2 antagonist
Butoxamine
118
T/F: If you had to choose, you should give selective beta blockers.
True
119
Give examples of non-selective a- and b-antagonists
Carvedilol | Labetalol
120
Enumerate the partial agonists
Pindolol | Acebutulol
121
What are some effects not related to beta-blockade?
Local anaesthetic action (blockade of Na+ channels) - acetabutulol, metoprolol, propanolol and labetalol Sotalol (Class III antiarrythmic drug) - K blockade
122
What antagonists are eliminated by hepatic metabolism and have relatively short half-lives?
Propanolol | Metoprolol
123
What antagonists are excreted unchanged by the kidneys and have longer half-lives?
``` Atenolol Nadolol (24 hours) ```
124
How long is the half-life of esmolol (beta 1)?
10 - 15 minutes
125
T/F: Beta blockers used to decrease BP by suppressing RAAS.
True
126
T/F: When given beta blockers, there is acute fall and chronic rise of peripheral resistance due to unopposed alpha-receptor mediated effects.
False Acute rise and chronic fall!
127
What are the effects of beta blockers on the endocrine system?
1. Mask tachycardia associated with hypoglycaemia 2. Inhibit lipolysis 3. Increase VLDL and decrease HDL
128
What are the effects of beta blockers on the CNS?
1. Treatment of severe migraine | 2. Solution for stage fright
129
T/F: Beta blockers decrease bleeding from oesophageal varices
True
130
T/F: Propanolol is capable of crossing the blood-brain barrier.
True
131
T/F: Atenolol is short-acting, while metoprolol is long-acting
False It's the other way around!
132
Name some contraindications to the use of beta blockers
1. Asthma or other bronchospastic condition 2. Severe bradycardia 3. AV block
133
Enumerate examples of indirect sympatholytics
Reserpine (inhibits VMAT) | Guanethidine (inhibits Ca2+-dependent release of NE)
134
What are the adverse effects of administering reserpine?
Psychiatric depression | Gastrointestinal disturbances
135
What are the adverse effects of administering guanethidine?
Severe orthostatic hypertension | Sexual dysfunction

[Ther 201] 2nd Exam Transes (5 decks)

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