Vasodilators Flashcards

1
Q

why does increasing K+ channel opening relax vascular smooth muscle

A

K+ flux sets the membrane potential
the longer the K+ channels are open, the closer the membrane potential is to K+ equilibrium potential
the closer the membrane potential is to the K+ equilibrium potential, the harder it is to depolarize the membrane enough to open voltage gated Ca2+ channels

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2
Q

drugs that are K+ channel agonists/openers

A

Minoxidil
Diazoxide
Adenosine

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3
Q

minoxidil metabolism

A

prodrug
activated in vivo by sulfotransferase 1A1

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4
Q

what is minoxidil used with

A

with loop diuretics and beta blockers

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5
Q

effects of minoxidil

A

very potent vasodilator - effective in severe, drug resistant forms of htn

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6
Q

what may contribute to minoxidil efficacy

A

cAMP PDE inhibition

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7
Q

minoxidil structure

A
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8
Q

diazoxide indication

A

used IV to tx acute htn

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9
Q

effects of diazoxide

A

very potent vasodilator - effective in severe, drug resistant forms of htn

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10
Q

diazoxide moa

A

inhibits release of insulin from pancreatic beta cells

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11
Q

diazoxide structure

A
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12
Q

what does adenosine bind to

A

A1 receptor- a GPCR

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13
Q

what does adenosine do

A

increases conductance of a K+ channel

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14
Q

what is adenosine used for

A

supraventricular arrhythmias
coronary stress test

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15
Q

where is the nitric oxide synthase

A

vascular endothelium

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16
Q

where does NO diffuse to

A

vascular smooth muscle

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17
Q

what is found in vascular smooth muscle

A

guanylate cyclase

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18
Q

how can NO directly relax smooth muscle

A

by being exogenously applied

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19
Q

where does NO bind and then what does it do

A

NO binds to heme iron prosthetic group in guanylate cyclase, stimulating production of cGMP and activating protein kinase G (cGKI)

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20
Q

how does protein kinase G relax smooth muscle

A

inhibition of L-type Ca2+ channels (Cav1.2)
stimulation of Ca2+ activated K channels (BKca)
decreased MLC phosphorylation (myosin phosphatase 1)
enhanced Ca2+ uptake in to ER (phospholamban)

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21
Q

what are features of organic nitrates

A

non-selective vasodilators
breakdown to NO
don’t require functional endothelium
acute or chronic admin

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22
Q

types of organic nitrates/nitrites

A
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23
Q

organic nitrates PK

A
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24
Q

organic nitrates indications

A

given sublingually in tx of acute angina attacks
given orally or transdermally for prolonged prophylaxis
tolerance occurs with continuous admin

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25
Q

pharmacogenetics of glycerol trinitrate

A

glu 504 Lys polymorphism in ALDH-2
glu 504 is 10x more efficient in metabolizing GTN

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26
Q

what likely accounts for lack of efficacy of GTN in large % of asian pop

A

30-50% of asian pop has at least one Lys 504 allele

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27
Q

what is the diff in activation of GTN and ISMN/ISDN

A

ISMN and ISDN activation is ALDH-2 independent

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28
Q

what is the mechanism of cell damage initiated by hyperglycemia

A

AGE precursor methylglyoxal inhibits vasorelaxation stimulated by acetylcholine/NO

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29
Q

sodium nitroprusside (SNP) indication

A

given IV for acute management of hypertensive crisis and severe decompensated hf

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30
Q

SNP effects

A

dilates veins and arterioles

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31
Q

SNP metabolism

A

metabolized in erythrocytes to NO, 4CN-, and cyanmethemoglobin

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32
Q

hydralazine effects

A

dilates arterioles preferentially

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33
Q

hydralazine moa

A

moa not clear
appears to interfere with release of Ca from the ER
may also prevent oxidation of NO

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34
Q

what can hydralazine induce

A

Lupus-like syndrome

35
Q

what does BiDil (the combo of hydralazine + ISDN) do

A

antioxidant activity potentiates vasodilatory activity of ISDN
BiDil decreases mortality in AA w CHF

36
Q

what is the human type B natriuretic peptide (BNP) drug

A

natrecor (nesiritide)

37
Q

natrecor indication

A

given IV in acutely decompensated HF

38
Q

what does natrecor bind to and do

A

binds to and activates membrane bound guanylate cyclase in vascular smooth muscle and endothelial cells

39
Q

where is natrecor metabolized

A

synthesized and secreted from heart muscle in response to increased blood volume

40
Q

natriuretic peptide mechanism

A
41
Q

neprilysin (a protease) inhibitor drug

A

sacubitril

42
Q

what is sacubitril

A

a prodrug activated by esterases

43
Q

sacubitril moa

A

prevents breakdown of BNP, enhancing its action (also angiotensin 2 and bradykinin)

44
Q

what is sacubitril not used with

A

ACE inhibitors

45
Q

sacubitril indication

A

tx hf

46
Q

sacubitril combo product

A

ARNI - combination with ARB valsartan (entresto)

47
Q

what drugs inhibit breakdown of cGMP/AMP

A

PDE

48
Q

PDE3 inhibitor structures

A
49
Q

what is the mechanism for controlling smooth muscle tone

A
50
Q

what drug class is amrinone/milrinone

A

PDE3 (cAMP) inhibitor

51
Q

amrinone/milrinone effect

A

direct positive inotropic effect on myocardium.
minimal chronotropic effect.
direct vasodilatory effect on vascular smooth muscle.

52
Q

how is amrinone/milrinone given

A

IV

53
Q

amrinone/milrinone indication

A

used mainly in ACUTE chf ONLY

54
Q

what is sildenafil a potent and specific inhibitor of

A

cGMP PDE5

55
Q

how selective is sildenafil for each PDE

A

10 fold more selective for PDE5 inhibition over PDE6 inhibition
4000 fold more selective for PDE5 inhibition over PDE3 inhibition

56
Q

what can PDE6 inhibition lead to

A

bluish vision

57
Q

what does sildenafil lack

A

systemic vasodilation

58
Q

PDE5 inhibitor structures

A

all very similar
vardenafil has extra methyl group and nitrogen

59
Q

levitra pk

A

shorter time to onset than viagra
more selective for PDE5 than viagra

60
Q

cialis pk

A

more selective for pde5 than viagra
longer duration of action than viagra or levitra

61
Q

why is PDE5 inhibitors CI w organic nitrates

A

both drugs increase accumulation of cGMP, leading to precipitous drop in BP

62
Q

endothelial signaling

A
63
Q

what are bosentan (tracleer) and macitentan (opsumit) used for

A

pulmonary arterial htn

64
Q

tracleer and opsumit moa

A

endothelin receptor antagonists
block both ETa (VSM) and ETb (VSM + endothel) receptors

65
Q

tracleer and opsumit MW

A

low

66
Q

ambrisentan (letairis) moa

A

blocks only ETa receptors

67
Q

what is letairis CI for

A

pregnancy

68
Q

what sex are tracleer, opsumit, and letairis available for

A

female

69
Q

PGI2, iloprost, selexipag effect

A

relax pulmonary vascular smooth muscle

70
Q

PGI2, iloprost, selexipag indication

A

tx pulmonary arterial htn

71
Q

PGI2 dosage form

A

IV

72
Q

iloprost dosage form

A

inhalation

73
Q

selexipag dosage form

A

oral

74
Q

PGI2, iloprost, selexipag structures

A
75
Q

riociguat (adempas) indication

A

tx pulmonary arterial htn

76
Q

riociguat (adempas) moa

A

potentiates NO effect
stimulates sGC activity allosterically
increases cGMP conc in VSM

77
Q

what is riociguat (adempas) not combined with

A

nitrates or PDE5 inhibitors

78
Q

riociguat (adempas) CI

A

pregnancy

79
Q

riociguat (adempas) risk

A

hemorrhage

80
Q

what is riociguat (adempas) substrate for

A

P-gp, CYP1A1, CYP3A

81
Q

what sex can take riociguat (adempas)

A

females only

82
Q

why are PDE5 inhibitors indicated for PAH

A

PDE5 is expressed in vascular smooth muscle of lungs
both are thought to enhance vasodilatory effect of NO

83
Q

which PDE5 inihibitors are indicated for PAH

A

sildanifil
cialis