Lecture 7: Adrenergic Agonists Flashcards

1
Q

Receptor a1

A

-signals via Gq
-found on vascular, GI smooth muscle, and heart, and liver
-mediates vasoconstriction

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2
Q

a1 agonist clinical use

A

-nasal decongestion
-vascular failure in shock and supraventricular tachycardia

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3
Q

a1 ANTAgonist clinical use

A

-hypertension
-benign prostatic hyperplasia
-pheochromocytoma

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4
Q

direct a1 AGONIST drugs

A

-phenylephrine
-oxymetazoline

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5
Q

Phenylephrine (Neosynephrine)

A

-direct a1 agonist
-substrate for MAO
-high first pass metabolism

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6
Q

Phenylephrine clinical use

A

-a1 agonist
-nasal decongestant (bad tho)
-mydriasis w/o cycloplegia
-pressor
-vasoconstrictor in regional anesthesia

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7
Q

Phenylephrine administration

A

-parenteral
-oral
-local

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8
Q

2-aralkylimidazolines

A

-direct a1 receptor agonist
-basicity of imidazoline ring cause compunds to exist in ionized form at physiological pH
-partial agonists

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9
Q

2-aralkylimidazolines types

A

-naphazoline
-tetrahydrozoline
-oxymetazoline (visine)

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10
Q

2-aralkylimidazoline clinical use

A

-admin topically to promote vasoconstriction
-nasal and ophthalmic decongestants

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11
Q

Imidazoline

A

-basic ring structure
-cation is resonance stable = more basic

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12
Q

Beta receptor signaling

A

-Gs
-activate adenylyl cyclase
-increase cAMP
-cAMP dependent protein kinase
-phosphorylation of ion channels

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13
Q

B1 receptor location

A

-heart
-kidney

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14
Q

B1 receptor effect on heart

A

-increase force of contraction (inotropy)
-increase HR (chronotropy)
-increase conduction velocity in AV node

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15
Q

B1 receptor effect on kidney

A

-increase renin release

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16
Q

B1 AGONIST clinical use

A

-shock
-congestive heart failure

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17
Q

B1 ANTAgonist clinical use

A

-hypertension
-angina
-arrhythmias
-congestive heart failure

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18
Q

B2 receptor location

A

-smooth muscle

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19
Q

B2 receptor effect

A

-relax smooth muscle esp bronchial
-vasoDILATION

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20
Q

B2 AGONIST clinical use

A

-asthma
-premature labor

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21
Q

B2 ANTAgonist clinical use

A

Glaucoma

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22
Q

B3 receptor location

A

-bladder

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23
Q

B3 receptor effect

A

-relaxation
-prevention of urination

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24
Q

B3 AGONIST clinical use

A

-overactive bladder

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25
Q

Non-selective B agonists

A

-isoproterenol (isuprel)

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26
Q

B1-selective B AGONISTs

A

-Dobutamine (Dobutrex)
-Dopamine (intropin) (MOA complex)

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27
Q

B2 selective AGONISTS

A

-Terbutaline (brethine, bricanyl)
-metaproterenol (metaprel, alupent)
-albuterol (proventil, ventolin)
-salmeterol (serevent)
-ritodrine (yutopar)

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28
Q

B3-selective AGONISTS

A

-mirabegron (myrbetriq)

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29
Q

Isoproterenol (Isuprel)

A

-non-selective B AGONIST
-bronchodilation
-increase cardiac output

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30
Q

Isoproterenol (Isuprel) metabolism

A

-by phase II conjugation reactions
-by COMT
-not sensitive to MAO

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31
Q

Isoproterenol administration

A

-oral
-parenteral
-local (inhaled)

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32
Q

isoproterenol use

A

-asthma
-COPD
-cardiostimulant

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33
Q

Isoproterenol Action

A

-B1 and B2 AGONIST
-increase Cardiac Output

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34
Q

Isoproterenol effect on peripheral vessels

A

-stimulate B2
-vasoDILATION
-reduce peripheral resistance (may lower BP)

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35
Q

Isoproterenol clinical use

A

-emergency use to increase HR
-patients with bradycardia or heart block
-patients with SYSTOLIC dysfunction, SLOW HR, high systemic vascular resistance: after cardiac surgery in patients who previously used B-blockers
-astma and COPD

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36
Q

Isoproterenol note

A

-not routinely used
-epinephrine and dopamine more common

37
Q

selectivity of adrenergic receptor agonists

A

SLide 37

38
Q

Response to decrease in Blood pressure

A

-activates sympathetic fibers
-activate B1 receptors = increase HR (reflex tachycardia)
-activate a1 receptors = vasoCONSTRICT blood vessels
-INHIBITS vagus (PSNS)

-net result=increase BP

39
Q

Response to increase in blood pressure

A

-INHIBITS sympathetic fibers
-activates VAGUS (PSNS) = decrease HR (reflex bradycardia)
-no effect on blood vessels

-net result = decrease BP

40
Q

BP= peripheral resistance x cardiac output

A

-resistance influenced by vasoconstriction/dilation
-output influenced by HR and stroke volume

41
Q

Norepinephrine effects

A

-decrease HR
-increase BP
-increase resistance

-a1,B1

42
Q

Epinephrine effects

A

-INcrease HR
-maintain BP
-slight DErease peripheral resistance

-a1, B1, B2

43
Q

Isoproterenol effects

A

-INcrease HR
-slight DEcrease BP
-DEcrease resistance

-B1, B2

44
Q

Selective B2 AGONists

A

-resorcinol derivatives
-bronchoDILATION
-cardiac effects only observed at high doses

45
Q

Selective B2 AGONist metabolism

A

-NOT by MAO or COMT
-longer duration of action than isoproterenol

46
Q

selective B2 agonist administration

A

-oral
-parenteral (only resorcinol derivatives)
-local (inhaled)

47
Q

selective B2 AGONist uses

A

-asthma
-COPD
-terbutaline used as tocolytic (prevent premature labor)

48
Q

STRUCTURES

A

STRUCTURES

49
Q

Resorcinol derivatives

A

-selective B2 AGONists
-metaproterenol
-terbutaline

50
Q

Meta hydroxymethyl derivatives

A

-selective B2 AGONISTS
-Albuterol
-Salmeterol

51
Q

Long acting B2 Agonists

A

-Salmeterol and Formoterol
-10 min and 5 min onset respectively
-longer duration
-INHALED
-use for long-term astma and COPD
-not acute treatment

52
Q

Problems with B2 receptor agonists

A

-minor cardiac stimulation

53
Q

Dobutamine

A

-MIXED B1 and a1 AGONIST
-dopamine derivative
-racemic
-racemic exerts stronger inotropic than chronotropic effect
-SHORT (2min) half life

54
Q

+ Dobutamine enatiomer

A

-potent B1 AGONIST

55
Q
  • Dobutamine enatiomer
A

-potent a1 AGONIST
-reduced potency for B by 10x

56
Q

Dobutamine metabolism

A

-by COMT and conjugation
-NOT sensitive to MAO

57
Q

Dobutamine administration

A

-IV infusion (why?)

58
Q

Dobutamine use

A

-acute heart failure
-shock
-lab stresss test

59
Q

Mirabegron

A

-B3 AGONIST
-use for overactive bladder
-also M3 ANTAgonist!

60
Q

Mirabegron problems

A

-slow onset (8 weeks)
-HTN

61
Q

a2 receptor signaling

A

-Gi pathway
-inhibit Ca
-decrease NT release

62
Q

a2 Agonist clinical use

A

-HTN
-pain
-glaucoma

63
Q

a2 receptor AGONISTs

A

-Clonidine
-Methyldopa
-Guanabenz
-Guanfacine
-Brimodine
-Apraclonidine
-Tizanidine

64
Q

Clonidine

A

-(phenylimino)imidazoline
-a2 AGONIST
-also imidazoline receptor

65
Q

Clonidine structure

A

-imidazoline ring
-basicity of guanidine froup decreased (pKa 13 to 8) bc attachment to dichlorophenyl ring

66
Q

Clonidine action

A

-a2 AGONIST
-in CNS: decrease SNS activity to heart and blood vessels
-presynaptic: decrease cAMP, inhibit Ca (decrease vesicular release), activate certain Ka channels (hyperpolarize

67
Q

Clonidine administration

A

-oral
-parenteral
-transdermal

68
Q

Clonidine clinical use

A

-HTN
-neuropathic pain
-opiate withdrawal
-ADHD

69
Q

Clonidine problems

A

-hypotension
-sedation
-dry mouth
-withdrawal sometimes after prolonged use

70
Q

a2 AGONIST effect

A

-reduce SNS
-inhibit NE release

71
Q

Decreased SNS effect

A

-DEcrease HR
-DEcrease contractility
-DEcrease renin release
-DEcrease vasoCONSTRICTION

72
Q

open ring imidazolidine a2 agonists

A

-Guanabenz
-Guanfacine

73
Q

Guanabenz and Guanfacine admin

A

oral

74
Q

Guanabenz and Guanfacine structure

A

-open ring imidazolidines
-2 atom bridge to guanidine group decreases pKa so drug is mostly non-ionized at physiological pH

75
Q

Guanabenz and Guanfacine clinical use

A

-HTN
-ADHD (guanfacine)

76
Q

Guanabenz half-life

A

6 hours

77
Q

-guanfacine and clonidine half life

A

-12-16 hours

78
Q

Methyldopa

A

-a2 AGONIST
-prodrug metabolized to agonist
-decrease SNS
-oral

79
Q

Methyldopate

A

-water soluble ester HCL salt
-used for parenteral solutions

80
Q

Methyldop(ate) uses

A

-HTN
-esp during pregnancy

81
Q

Methyldopa metabolism

A

slide 52

82
Q

Brimodine action

A

-a2 AGONIST
-acts on ciliary body
-inhibits aq humor production (acute)
-stimulate aq humor outflow (chronic)

83
Q

Brimodine use

A

-Glaucoma (ophtalmic)

84
Q

Brimonidine problems

A

allergic conjunctivitis

85
Q

Meds for Glaucoma

A

-brimonidine
-apraclonidine (para NH2 on clonidine)

86
Q

Tizanidine

A

-a2 AGONIST

87
Q

tizanidine use

A

-muscle spasticity

88
Q

tizanidine adverse effects

A

-sedation
-Na+ and water retention
-dry mouth
-withdrawal