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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

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
Q

Where are beta-3 receptors located?

A

Postsynaptic effector cells in lipocytes

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26
Q

What is the mechanism of the beta adrenergic receptors?

A

Gs protein stimulates adenylyl cyclase to produce more cAMP

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27
Q

T/F: Alpha-1 and beta-2 have opposite effects.

A

True

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28
Q

What are the most important dopamine receptors?

A

D1 and D2

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29
Q

Where are the dopamine receptors found?

A

CNS
Brain
Splanchnic & renal vasculature

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30
Q

Which dopamine receptors increase cAMP? decrease cAMP?

A

D1 & D5 - increase cAMP (Gs)

D2 to D4 - decrease cAMP (Gi)

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31
Q

Where is D1 found?

A

Smooth muscles (stimulation increases cAMP)

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32
Q

Where is D2 found?

A

Nerve endings

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33
Q

What is the basis for adrenoreceptor classification?

A

Structure-activity relationships

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34
Q

What is notable in the chemical structure of epinephrine?

A

It has a methyl group.

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35
Q

What is notable in the chemical structure of norepinephrine?

A

It has no methyl group.

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36
Q

What is notable in the chemical structure of isoproterenol?

A

It has a isopropyl group.

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37
Q

What is the graph profile of the beta-1 receptor?

A

Iso > E >/= NE (Effect on Force of Contraction)

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38
Q

What is the graph profile of the beta-2 receptor?

A

Iso > E&raquo_space; NE (Effect on Bronchodilation)

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39
Q

What is the action of an adrenergic agonist?

A

Inhibits the degradation of cAMP

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40
Q

What is the graph profile of the alpha-1 receptor?

A

E >/= NE&raquo_space; ISO (Effect on Bronchoconstriction)

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41
Q

Response of any cell or organ to sympathomimetic depends on what?

A

Density and proportion of adrenergic receptors

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42
Q

What are the potential actions of the adrenergic receptors?

A
  1. Peripheral excitation
  2. Peripheral inhibition
  3. Cardiac excitation
  4. Metabolic action
  5. Endocrine action
  6. CNS action
  7. Prejunctional action
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43
Q

What are the tissue distribution of and actions mediated by the alpha-1 receptor?

A 
Vascular smooth muscle - contraction
Pupillary dilator muscle - contraction
Pilomotor smooth muscle - erection
Prostate - contraction
Heart - inc. force of contraction
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44
Q

What are the tissue distribution of and actions mediated by the alpha-2 receptor?

A

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

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45
Q

What are the tissue distribution of and actions mediated by the beta-2 receptor?

A

Respiratory, uterine and vascular smooth muscle - relaxation
Skeletal muscle - K+ uptake
Liver - glycogenolysis
Uterine smooth muscle - relaxation

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46
Q

What are the tissue distribution of and actions mediated by the beta-1 receptor?

A

Heart - increased force & rate of contraction

JG Cells - increased renin release

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47
Q

What are the tissue distribution of and actions mediated by the beta-3 receptor?

A

Fat cells - lipolysis

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48
Q

What are the tissue distribution of and actions mediated by the D1 receptor?

A

Smooth muscle - dilates renal blood vessels

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49
Q

What are the tissue distribution of and actions mediated by the D2 receptor?

A

Nerve endings - modulates transmitter release

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50
Q

T/F: D1 can improve urine output.

A

True

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51
Q

Enumerate the direct-acting selective adrenergic agonists and the receptors they target.

A 
Phenylephrine - alpha 1
Clonidine - alpha 2
Dolbutamine - beta 1
Albuterol/terbutaline - beta 2
D1 - Fenoldopam
D2 - Bromocriptine
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52
Q

Enumerate the direct-acting non-selective adrenergic agonists and the receptors they target.

A

Oxymetazoline - alpha 1 & 2
Isoproterenol - beta 1 & 2
Epinephrine - alpha 1 & 2, beta 1 & 2
Norepinephrine - alpha 1 & 2, beta 1

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53
Q

Enumerate the indirect-acting releasing agents

A

Amphetamine

Tyramine

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54
Q

Enumerate the indirect-acting uptake inhibitors

A

Cocaine

Tricyclic antidepressants

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55
Q

Enumerate the mixed-acting adrenergic agonists and the receptors they target.

A

Ephedrine - alpha 1 & 2, beta 1 & 2 + releasing agent

Dopamine - D1 & 2, alpha and beta + releasing agent

56
Q

T/F: Receptor specificity/selectivity is absolute.

A

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
Q

Describe pheochromocytoma

A
  1. Increased production of NE

2. Request for urine vancodilic acid

58
Q

Describe phenylethylamine

A
  1. Selective alpha-1 agonist w/ hydroxyl group at C3
  2. Found in chocolates
  3. Increases dopamine levels at mesolimbic pleasure centres
59
Q

Describe tyramine

A
  1. Monoamine compound derived from tyrosine

2. Releases monoamines such as dopamine, NE and E

60
Q

What have the highest affinity to beta receptors?

A

Catecholamines

61
Q

What does increasing the size of the alkyl group attached to the amino group do?

A

Increases affinity for beta receptors and decreases affinity for alpha receptors

62
Q

T/F: All adrenergic compounds are catecholamines.

A

False

63
Q

T/F: Maximal alpha and beta receptor binding is found in catecholamines.

A

True

64
Q

Why is phenylephrine given parenterally?

A

It is not a catecholamine. It only has 1 OH group.

65
Q

Describe phenylephrine

A
  1. Arterial vasoconstriciton
  2. Nasal decongestant
  3. Mydriatic
66
Q

Decreased substitution causes?

A
  1. Increased bioavailability (spared from COMT inactivation in gut and liver)
  2. Increased distribution to CNS (ephedrine & amphetamine)
67
Q

T/F: Phenylisopropanols are given intravenously.

A

True

68
Q

T/F: NE cannot be given subcutaneously.

A

False

69
Q

What is the effect of substitution at the alpha carbon?

A
  1. Block oxidation by MAO
  2. Prolong action
  3. Displace catecholamines from storage sites
70
Q

What is the effect of substitution at the beta carbon?

A
  1. Direct acting agonists usually have this.

2. Important for storage of sympathomimetic amines

71
Q

Enumerate the alpha 1 agonists

A

Phenylephrine
Midodrine
Methoxamine

72
Q

Enumerate the alpha 2 agonists

A

Clonidine
Methylnorepinephrine
Methyldopa

73
Q

Enumerate the mixed alpha and beta agonists

A

Epinephrine

Norepinephrine

74
Q

Enumerate the beta 1 agonists

A

Dobutamine

75
Q

Enumerate the beta 2 agonists

A

Terbutaline

Albuterol

76
Q

Enumerate the dopamine agonists

A 
Dopamine
Fenoldopam (D1 over D2)
77
Q

T/F: Isoproterenol possesses the same affinity for both beta 1 and 2 receptors.

A

True

78
Q

Describe dopamine

A
  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
Q

What are the effects of a beta 1 agonist on the CVS?

A
  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
Q

What are the effects of dobutamine?

A

+ isomer - beta 1 agonist, alpha 1 antagonist, vasodilation

- isomer - alpha 1 agonist, beta 1 antagonist, vasoconstriction

81
Q

What are the effects of a beta 2 agonist on the CVS?

A
  1. Vasodilation

2. Reflex response in heart rate

82
Q

What are the effects of an alpha 1 agonist on the CVS?

A
  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
Q

What are the effects of an alpha 2 agonist on the CVS?

A
  1. Reduction in BP (decreased NE & medulla activity)

2. Vasodilation

84
Q

How does an alpha 2 agonist reduce blood pressure?

A
  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
Q

Summarize the CVS effects of sympathomimetics on heart rate

A

Isoproterenol - increase (dec. TPR)
Norephephrine - decrease (inc. TPR)
Low dose epinephrine - increase (dec. TPR)
High dose epinephrine - decrease (inc. TPR)

86
Q

What is the effect of a beta 2 agonist on the respiratory tract?

A

Bronchodilation

87
Q

What are the effects of an alpha 1 agonist on the respiratory tract?

A
  1. Vasoconstriction of blood vessels of URT

2. Nasal decongestion

88
Q

Why shouldn’t alpha 1 agonists be taken by hypertensive patients?

A

It may aggravate the hypertension.

89
Q

What are the effects of an alpha 2 agonist on the gastrointestinal tract?

A
  1. Reduce release of ACh (decrease BP)
  2. Enhance salt and water reabsorption
  3. Treatment of diarrhoea in diabetics with autonomic neuropathy (clonidine)
90
Q

What are the effects of a beta 2 agonist on the genitourinary tract?

A
  1. Relax uterine smooth muscle

2. Relax bladder wall

91
Q

What are the effects of an alpha 1 agonist on the genitourinary tract?

A
  1. Constriction of the base

2. Hypertension

92
Q

What are the effects of beta agonists on metabolism?

A
  1. Increase glycogenolysis
  2. Increase lipolysis
  3. Increase insulin (beta 2) and renin (beta 1) secretion
  4. Promotes potassium re-uptake
93
Q

What are the effects of an alpha 2 agonist on metabolism?

A
  1. Decreases release of NE
  2. Decreases insulin and renin action
  3. Inhibition of lipolysis
94
Q

What is the effect of a beta receptor agonist on the eye?

A

Relaxation of ciliary muscle with decrease in accommodation

95
Q

What are the effects of an alpha receptor agonist on the eye?

A
  1. Mydriasis

2. Decreases intraocular pressure

96
Q

Phenylephrine causes mydriasis without what?

A

Cyclopegia

97
Q

What is the effect of catecholamines at a high infusion rate on the CNS?

A

Feeling of impending disaster

98
Q

What are the effects of non-catecholamines on the CNS?

A 
Mild improvement in alertness
Elevation of mood
Insomnia
Euphoria
Anorexia
99
Q

What is the mechanism of action of amphetamine?

A

Displaces norepinephrine from vesicles into the cytosol and blocks MAO

This results in hyperactivity and narcolepsy in children!

100
Q

Compare dobutamine and isoproterenol

A

Dobutamine is more inotropic than chronotropic.

101
Q

Describe the toxicity of pressor agents

A

Marked increase in BP
Cardiac ischemia and failure
Heart failure

102
Q

Describe the toxicity of beta agonists

A

Sinus tachycardia

Ventricular arrythmias

103
Q

Describe the toxicity of amphetamines

A

Restlessness
Tremors
Anxiety
Paranoid state

104
Q

Describe the toxicity of cocaine

A

Convulsions
Hemorrhage
Arrythmias

105
Q

Methyldopa is the prodrug of?

A

Alpha-methylnorepinephrine

106
Q

Describe: Clonidine

A
  1. Tested as topical nasal decongestant
  2. Anti-hypertensive effect
  3. Activates alpha 2 receptors in lower brainstem
107
Q

Enumerate the selective alpha 1 antagonists

A

Prazosin
Terazosin
Doxazosin

108
Q

Give a selective alpha 2 antagonist

A

Yohimbine

109
Q

Enumerate the non-selective alpha antagonists

A

Phenoxybenzamine (irreversible antagonist)

Phentolamine (reversible antagonist)

110
Q

What are the effects of an alpha antagonist on the CVS?

A
  1. Relaxes smooth muscle
  2. Decreases PVR, venous return and blood pressure
  3. Orthostatic hypotension as a side effect
  4. Blockade of RAS
111
Q

T/F: Phenoxybenzamine has a higher affinity for alpha 1 than alpha 2 receptors.

A

True

112
Q

What is the first selective alpha 1 antagonist?

A

Prazosin

113
Q

Why should alpha receptor blockade come before beta receptor blockade?

A

This prevents an increase in BP from vasoconstriction.

114
Q

T/F: A low dose of epinephrine causes it to bind to beta receptors.

A

True

115
Q

Give an example of a non-selective beta antagonist

A

Propanolol

116
Q

Enumerate the selective beta 1 antagonists

A 
Betaxolol
Esmolol
Acebutolol (paritla agonist)
Atenolol
Metoprolol

BEAM!

117
Q

Give an example of a selective beta 2 antagonist

A

Butoxamine

118
Q

T/F: If you had to choose, you should give selective beta blockers.

A

True

119
Q

Give examples of non-selective a- and b-antagonists

A

Carvedilol

Labetalol

120
Q

Enumerate the partial agonists

A

Pindolol

Acebutulol

121
Q

What are some effects not related to beta-blockade?

A

Local anaesthetic action (blockade of Na+ channels) - acetabutulol, metoprolol, propanolol and labetalol

Sotalol (Class III antiarrythmic drug) - K blockade

122
Q

What antagonists are eliminated by hepatic metabolism and have relatively short half-lives?

A

Propanolol

Metoprolol

123
Q

What antagonists are excreted unchanged by the kidneys and have longer half-lives?

A 
Atenolol
Nadolol (24 hours)
124
Q

How long is the half-life of esmolol (beta 1)?

A

10 - 15 minutes

125
Q

T/F: Beta blockers used to decrease BP by suppressing RAAS.

A

True

126
Q

T/F: When given beta blockers, there is acute fall and chronic rise of peripheral resistance due to unopposed alpha-receptor mediated effects.

A

False

Acute rise and chronic fall!

127
Q

What are the effects of beta blockers on the endocrine system?

A
  1. Mask tachycardia associated with hypoglycaemia
  2. Inhibit lipolysis
  3. Increase VLDL and decrease HDL
128
Q

What are the effects of beta blockers on the CNS?

A
  1. Treatment of severe migraine

2. Solution for stage fright

129
Q

T/F: Beta blockers decrease bleeding from oesophageal varices

A

True

130
Q

T/F: Propanolol is capable of crossing the blood-brain barrier.

A

True

131
Q

T/F: Atenolol is short-acting, while metoprolol is long-acting

A

False

It’s the other way around!

132
Q

Name some contraindications to the use of beta blockers

A
  1. Asthma or other bronchospastic condition
  2. Severe bradycardia
  3. AV block
133
Q

Enumerate examples of indirect sympatholytics

A

Reserpine (inhibits VMAT)

Guanethidine (inhibits Ca2+-dependent release of NE)

134
Q

What are the adverse effects of administering reserpine?

A

Psychiatric depression

Gastrointestinal disturbances

135
Q

What are the adverse effects of administering guanethidine?

A

Severe orthostatic hypertension

Sexual dysfunction

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

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