Adrenergic Agonists 2 Flashcards

1
Q

Norepinephrine inactivation by

A

neuronal uptake of COMT and MAO (uptake 1)

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2
Q

PK of NE:

A

POLAR, found in urine, poorly absorbed in gut

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3
Q

Receptor selectivity of NE

A

a1=a2; B1&raquo_space; B2

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4
Q

Receptor selectivity of E

A

a1=a2; B1 = B2

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5
Q

Receptor selectivity of Phenylephrine, Methoxamine

A

a1>a2&raquo_space;» B (alpha agonists)

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6
Q

Receptor selectivity of Clonidine, Methyldopa

A

a2>a1&raquo_space;» B (alpha agonists)

alpha 2 agonists decrease sympathetic outflow –> decreased TPR and HR

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7
Q

Receptor selectivity of Dobutamine

A

B1&raquo_space; B2&raquo_space;» a (beta agonist)

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8
Q

Receptor selectivity of Isoproterenol

A

B&raquo_space;» a (strong beta agonist)

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9
Q

Receptor selectivity of Terbutaline, Albuterol

A

B2&raquo_space; B1&raquo_space;» a (beta agonists)

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10
Q

Receptor selectivity of Dopamine

A

D1=D2&raquo_space; B&raquo_space; a

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11
Q

Receptor selectivity of Fenoldopam

A

D1&raquo_space; D2

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12
Q

Norepinephrine CVS effects?

A

Increased PVR –> Increased SP/DP
Increased SV
CO variable

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13
Q

Which has the greater effect on BP? NE or E? Why?

A

Norepinephrine because of increase in PVR (predominant alpha receptor activation–NE does not at on B2 which is responsible for vasodilation)

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14
Q

Why does NE result in reflex bradycardia but not E?

A

Epi will not cause a tremendous increase in BP because it acts on B2 receptors responsible for vasodilation. Norepi will act on alpha 1 receptors (blood vessels) and beta 1 (heart) but not beta 2. The increase in blood pressure evokes a baroreceptor vagal reflex in bradycardia.

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15
Q

How can NE cause tissue necrosis and sloughing when extravasated through IV?

A

Vasoconstriction

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16
Q

Impaired circulation due to NE can be relieved by what?

A

phentolamine (alpha receptor antagonist)

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17
Q

What is the metabolic precursor of NE and E?

A

Dopamine

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18
Q

What are the effects of low doses of Dopamine on CVS?

A

Vasodilation (D1 receptors at renal, mesenteric, and coronary beds)

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19
Q

Cardiogenic shock is treated with?

A

DA > isoproterenol

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20
Q

What are the effects of moderately high doses of Dopamine on CVS?

A

Beta 1 receptor activation (heart) –> +inotropy with MINIMAL TACHYCARDIA

Alpha 1 activation (vascular) –> vasoconstriction

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21
Q

What can dopamine cause the release of at nerve terminals?

A

NE

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22
Q

What are the effects of low doses of Dopamine on renal system?

A

D1 stim –> natriuresis –> diuresis

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23
Q

This is a benzazepine derivative and agonist for peripheral D1 receptors with moderate affinity for a2 receptors.

A

Fenoldopam

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24
Q

Which drug has dopamine receptor affinity and is used as a vasodilator in severe HTN?

A

Fenoldopam

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25
Q

Synthetic analog of dopamine:

A

Dopexamine

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26
Q

This has D1 and D2 affinity and inhibits catecholamines uptake.

A

Dopexamine (also B2 activity)

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27
Q

Therapeutic uses of Dopexamine:

A

severe CHF, cardiogenic and septic shock (similar to dopamine)

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28
Q

Powerful beta receptor agonist. Acts on all beta receptors.

A

Isoproterenol

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29
Q

Administration of isoproterenol?

A

Parenteral or aerosol

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30
Q

Metabolism of isoproterenol?

A

In liver by COMT.

POOR substrate for MAO

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31
Q

What are the effects of isoproterenol on the CVS?

A

Decrease DP –> Decrease BP (SP varies)

+inotropic/chronotropic effects (B1) –> increase CO

Vasodilation (B2) –> decreased PVR

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32
Q

What are the effects of isoproterenol on smooth muscles?

A

Bronchodilation (B2)

Vasodilation in skeletal muscles (B2)

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33
Q

B2 agonists are effective in asthmatics because of two reasons. What are they?

A

1) bronchodilation

2) inhibition of antigen-induced release of histamine and other inflammatory mediators

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34
Q

Therapeutic uses of isoproterenol:

A

1) Emergency bradycardia or heart block, in anticipation of cardiac pacemaker insertion or in patients with ventricular arrythmias
2) Replaced in treatment of asthma, COPD, and shock

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35
Q

Beta agonist used clinically as a racemate preparation

A

Dobutamine

36
Q

Which Dobutamine isomer is a more potent beta agonist?

A

(+) isomer

37
Q

Which Dobutamine isomer is a potent alpha 1 agonist?

A

(-) isomer

38
Q

Which Dobutamine isomer is an alpha 1 antagonist?

A

(+) isomer

39
Q

Dobutamine selective for beta 1 or beta 2?

A

Selective beta 1

40
Q

Effects of dobutamine is similar to _____ but with less ____

A

dopamine; tachycardia

41
Q

Dopamine at high doses = vaso____?

Dopamine at low doses = vaso____?

A

high dose –> vasoconstriction (A1 r)

low dose –> vasodilation (D1 r)

42
Q

Which CVS effect of dobutamine is more prominent? Inotropic or Chronotropic

A

Inotropic (alpha 1 r)

43
Q

Therapeutic uses for Dobutamine:

A

SHORT TERM: cardiac compensation in post-cardiac surgery or CHF or acute MI

44
Q

Contraindications for Dobutamind

A

idopathic hypertrophic subaortic stenosis

45
Q

What beta 2 selective agonist is used for SHORT-TERM prevention of pre-term labor as well as a bronchodilator?

A

Terbutaline

46
Q

Aside from short-term prevention of pre-term labor what else can Terbutaline be used for?

A

As a bronchodilator

47
Q

Differences between Albuterol/Salbutamol and Salmeterol?

A

Salbutamol/Albuterol: Short-acting, fast onset

Salmeterol: Prolonged action, SLOW onset (not suitable for status asthmaticus). Lipophilic. HIGHLY selective for Beta 2.

48
Q

Drug of choice for Nocturnal asthma:

A

Salmeterol + Formoterol

49
Q

What long-acting B2 agonist with fast onset is used for nocturnal asthma?

A

Formoterol

50
Q

Long-acting beta 2 agonist that may cause death or near death experience from increased CVS activity

A

Arformoterol

51
Q

Which beta 2 agonist is used ONLY as a uterine relaxant to arrest premature labor and prolong pregnancy

A

Ritodrine

52
Q

ULTRA LONG ACTING Beta 2 agonist with fast onset of action used ONLY for COPD

A

Indacaterol

53
Q

Which class or subclass of drugs mainly causes vasoconstriction –> increased PVR and BP, causes pupillary dilator contraction, intestinal and bladder sphincter contraction

A

alpha 1 agonists

54
Q

Selective alpha agonist used as Nasal decongestant. Which alpha type?

A

Phenylephrine, alpha 1

55
Q

Why is Phenylephrine not a catecholamine?

A

Lacks a -OH group at position 4. Catecholamines have -OH groups at 3 and 4.

56
Q

Why does Phenylephrine have a longer duration of action than catecholamines?

A

It is not inactivated by COMT

57
Q

Therapeutic uses of Phenylephrine aside from nasal decongestion?

A

Mydratic agent.
Hemostatic agent.
Vasopressor (increase in BP results in reflex bradycardia)

58
Q

What drug is used to treat paroxysmal supraventricular tachycardia?

A

Phenylephrine (lowers HR)

59
Q

Repeated use of topical nasal decongestants ultimately results in what?

A

Rebound congestion:
intense vasocostriction –> tissue hypoxia –> local mediator release –> vasodilation –> hyperemia –> congestion

OR receptor desensitization –> beta response predominates over alpha

60
Q

Long acting topical nasal decongestants:

A

Oxymetazoline (important), Xylometazoline

61
Q

Short acting topical nasal decongestants

A

Tetrahydrozoline, Nephazoline

62
Q

Which oral nasal decongestant can cause hemorrhagic strokes at high doses?

A

Phenylpropanolamine

63
Q

Which oral nasal decongestant is highly regulated for its role in shabu/methampetamine manufacturing?

A

Pseudoephedrine

64
Q

Active metabolite of midodrine?

A

desglymidodrine

65
Q

Primary indication is treatment of patients with autonomic insufficiency & orthostatic hypotension

A

Midodrine

66
Q

Frequent complication of midodrine?

A

supine hypertension

67
Q

Mixed-acting sympathomimetics:

A

epinephrine (direct)

ephedrine (direct on both, with additional indirect on alpha)

68
Q

Which mixed-acting sympathomimetic is resistant to enzyme?

A

ephedrine

epinephrine is sensitive

69
Q

Which mixed-acting sympathomimetic is polar?

A

epinephrine

70
Q

Which mixed-acting sympathomimetic crosses BBB?

A

ephedrine

71
Q

Which mixed-acting sympathomimetic has longer duration?

A

ephedrine

72
Q

Which mixed-acting sympathomimetic is more efficacious?

A

epinephrine

73
Q

In case of ephedrine toxicity, what should be done?

A

Since ephedrine is a weak base, the urine should be acidified with ascorbic acid or ammonium chloride to render it more ionized.

74
Q

MoA of indirect-acting sympathomimetics?

A

1) enter SNS nerve endings and displace stored catecholamines or DA
2) inhibit catecholamine reuptake

75
Q

Its D-isomer is more potent than its L-isomer.

A

Amphetamine

76
Q

Used for narcolepsy, ADHD, and to suppress appetite. Dependence forming.

A

Amphetamine

77
Q

Contraindication of methylphenidate

A

acute angle glaucoma (promotes NE release, aggravating glaucoma)

78
Q

Tyramine’s MoA?

A

Indirect sympathomimetic action. Promotes release of stored catecholamines.

79
Q

This class of drugs prevent uptake 1.

A

Catecholamine reuptake inhibitors.

80
Q

Atomoxetine: class?
Moa?
Therapeutic use?

A

Catecholamine reuptake inhibitor.
Increases available NE in noradrenergic synapses.
ADHD.

81
Q

This drug is similar to atomoxetine

A

Reboxitine

82
Q

Only local anaesthetic agent with sympathomimetic effects

A

Cocaine

83
Q

Which serotonin and NE reuptake inhibitors are used for Tx of obesity?

A

Sibutramine

84
Q

Which serotonin and NE reuptake inhibitors are used for Tx of fibromyalgia?

A

Milnacipran

85
Q

Which serotonin and NE reuptake inhibitors are used for Tx of depression? Which is only depression.

A

Duloxetine for depression only. Milacipran can be used as an antidepressant as well as for fibromyalgia.

86
Q

alpha 2 agonist used in opiate withdrawal

A

clonidine

87
Q

alpha 2 agonist used in pregnancy hypertension

A

methyldopa