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Therapeutics 2 - Exam 5 > vasodilators > Flashcards

vasodilators Flashcards

hockerman

1
Q

what are the vasodilators that regulate membrane potential?

A

K+ channel agonists/openers (minoxidil, diazoxide)
adenosine
they reduce voltage-gated Ca2+ channel activity

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2
Q

what is the MOA of K+ channel agonsits?

A

K+ flux sets the membrane potentional –> The longer K+ channels are open, 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+ channel

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3
Q

what is minoxidil?

A

K+ channel opener and potent vasodilator activated in vivo by sulfotransferase 1A1
effective in severe, drug resistant forms of HTN

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4
Q

what drugs are used concurrently with minoxidil?

A

loop diuretics
beta blockers

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5
Q

what are the SE of minoxidil?

A

hypertrichosis

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6
Q

what is diazoxide?

A

K+ channel opener and potent vasodilator used IV to treat acute HTN or severe drug resistant form of HTN

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7
Q

what is the MOA of diazoxide in hypoglycemia?

A

inhibits release of insulin from pancreatic beta-cells, which treats hypoglycemia secondary to hyperinsulinemia

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8
Q

what is adenosine?

A

nucleoside given IV that binds to A1 receptor (GPCR)
increases conduction of a K+ channel to induce relaxation and hyperpolarization

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9
Q

what are the indications of adenosine?

A

coronary stress test
supraventricular arrhythmias

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10
Q

how does the vascular smooth muscle hyperpolarize?

A

via adenosine
G-beta, gamma binds and activates G-protein activated inwardly rectifying K+ channel (GIRK) –> conducts K+ efflux –> membrane hyperpolarizes

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11
Q

what vasodilators stimulate nitric oxide production?

A

organic nitrates/nitrites
hydralazine
human type B natriuretic peptide (BNP)
sacubitril

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12
Q

what is eNOS?

A

isoform of nitric oxide synthase that is located in vascular endothelium
activated by Ca2+-CAM

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13
Q

where does nitric oxide diffusion take place?

A

vascular smooth muscle (directly relaxes sm)

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14
Q

where is guanylate cyclase located?

A

vascular smooth muscle

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15
Q

what did nitric oxide use to be called?

A

endothelial derived relaxing factor (EDRF)

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16
Q

what is a partial inhibitor of acetylcholine?

A

L-NMMA

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17
Q

what drug relaxes smooth muscle via nitric oxide?

A

acetylcholine

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18
Q

how does smooth muscle relax via nitric oxide?

A

nitric oxide binds to heme iron prosthetic group in guanylate cyclase –> stimulates the production of cGMP and activates protein kinase G (cGKI)

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19
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 into ER (phospholamban)

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20
Q

what are organic nitrates?

A

non-selective vasodilators that breakdown nitric oxide via bioactivation for acute or chronic administration

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21
Q

what are the types of organic nitrates/nitrites?

A

amylnitrite
glyceryl trinitrate (GTN)
pentaerythritol tetranitrate (PETN)
isosorbide dinitrate
isosorbide mononitrate
nitroprusside

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22
Q

what is PK of GTN?

A

3 minute half life
under 1% oral bioavailability

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23
Q

what is the PK of isosorbide dinitrate?

A

10 minute half life
20% oral bioavailability

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24
Q

what is the PK of isosorbide mononitrate?

A

280 minute half life
100% oral bioavailability

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25
Q

what are organic nitrates used for?

A

given sublingually for acute attacks of angina
given orally/transdermally for prolonged prophylaxis
tolerance occurs with continuous administration

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26
Q

what is sodium nitroprusside (SNP)?

A

vasodilator (veins and arterioles) given IV for acute management of HTN crisis and severe decompensated HF

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27
Q

what is the metabolism of sodium nitroprusside?

A

metabolized in erythrocytes to nitric oxide, 4 CN-, and cyanmethemoglobin
limits duration of treatment due to cyanide exposure

28
Q

what is rhodanase?

A

enzyme that converts CN- to be less toxic

29
Q

what is the effects of CN-?

A

inhibits oxidative metabolism
can lead to lactic acid accumulation

30
Q

what is the MOA of hydralazine?

A

dilates arterioles preferentially
appears to interfere with release of calcium from the ER
may prevent nitric oxide oxidation

31
Q

what are the effects of hydralazine?

A

lupus-like syndrome

32
Q

how is hydralazine administered?

A

oral or IV

33
Q

what is BNP?

A

human type B natriuretic peptide
vasodilator that binds to and activates membrane-bound guanylate cyclase in vascular smooth muscle and endothelial cells

34
Q

wha tis neprilysin?

A

enzyme that cleaves BNP

35
Q

how is BNP synthesized and secreted?

A

from heart muscle in response to increased blood volume

36
Q

what is sacubitril?

A

inhibitor of neprilysin (protease) and prodrug activated by esterases that prevents to breakdown of BNP

37
Q

what is the indication of sucubitril?

A

heart failure

38
Q

what is CI with sacubitril?

A

not used with ACE inhibitors

39
Q

what are phosphodiesterase inhibitors?

A

vasodilators that inhibit the break down of cGMP/AMP

40
Q

what drugs are PDE3 inhibitors?

A

amrinone
milrinone

41
Q

what drugs are PDE5 inhibitors?

A

diypyridamole
sildenafil (viagra)
tadalafil (Cialis)
vardenafil (levitra)

42
Q

what are the inotropic and chronotropic effects of amrinone/milrinone?

A

direct positive inotropic effect on myocardium
minimal chronotropic effect

43
Q

what are amrinone and milrinone?

A

cAMP PDE inhibitors
direct vasodilators given IV for acute treatment of chronic HF

44
Q

what is the selectivity of sildenafil?

A

10 fold and 4000 fold inhibition of PDE5 over PDE6 (retina) and PDE3 (CV) respectively
lack of systemic vasodilation

45
Q

what are the SE of sildenafil?

A

blurred vision

46
Q

where PDE5 predominantly located?

A

corpus cavernosum

47
Q

what is the PK of levitra?

A

faster onset and more selective for PDE5 than viagra

48
Q

what is the PK of cialis?

A

more selective for PDE5 than viagra
longer duration than viagra or levitra

49
Q

what are the CI of PDE5 inhibitors?

A

organic nitrates due to both drugs increasing the accumulation of cGMP which drops BP substaintly

50
Q

what are vasodilator drugs used in pulmonary arterial HTN?

A

endothelin antagonists
PG12 analogs
guanylyl cyclase activators
PDE5 inhibitors
activin neutralizers

51
Q

how does PAH affect endothelin signaling?

A

increases it

52
Q

what is MOA of bosentan (Tracleer) and macitentan

A

specific low MW endothelin receptor antagonists that block both Eta (VSM) and ETb (VSM and endothel) receptors

53
Q

what is MOA of ambrisentan?

A

endothelin receptor antagonist
blocks only ETa receptors

54
Q

what is the CI of endothelin receptor antagonists?

A

pregnancy
hepatotoxicity (bosentan)

55
Q

what is the indication of endothelin receptor antagonists?

A

pulmonary arterial hypertension (PAH)

56
Q

what is the MOA of smooth muscle relaxation?

A

Activation of GPCRs –> increases cAMP –> activates PKA –> inactivates MLCK –> reducing muscle contraction and promoting smooth muscle relaxation

57
Q

what is the PK of prostacyclin analogs?

A

PG12 –> half life 3 to 5 minutes; IV
treprostinil –> half life 4 hours: oral/IV
iloprost –> half life 30 minutes; inhalation
selexipag –> half life 6-13 hours; oral/IV

58
Q

what drugs are prostacyclin analogs?

A

PG12 (epoprostenol)
treprostinil (remodulin)
iloprost (ventavis)
selexipag (uptravi)

59
Q

what is the MOA of prostacyclin analogs?

A

relax pulmonary vascular SM

60
Q

what is the indication of prostacyclin analogs?

61
Q

what is riociguat?

A

adempas
allosteric activator of sGC and substrate for P-gp, CYP1A1/3A
used for pulmonary HTN

62
Q

what are the effects of riociguat?

A

potentiates the effect of NO
stimulates sGC activity allosterically
increase cGMP concentration in VSM

63
Q

what are the CI of riociguat?

A

nitrates
PDE inhibitors
pregnancy

64
Q

what is the warning of riociguat?

A

risk of hemorrhage

65
Q

where is PDE5 located?

A

vascular smooth muscle of lungs

66
Q

why are viagra and cialis indicated for PAH?

A

they enhance vasodilatory effects of nitric oxide

Therapeutics 2 - Exam 5 (14 decks)

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