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Pharmacology > Part 23: Vasodilators > Flashcards

Part 23: Vasodilators Flashcards

1
Q

in vascular smooth muscle, the interaction between ___ and ___ causes contraction, resulting in vasoconstriction

A

myosin and actin

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2
Q

during membrane depolarization of vascular smooth muscle cells, large amounts of ____ ions come in through ____ channels

A

Ca; voltage gated Ca channels

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3
Q

Ca can also enter BV smooth muscle cells through the ___- exchanger where ___ is removed from the cytoplasm and ca enters

A

Na/Ca (NCX); Na

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4
Q

compared to the voltage-gated Ca channels, the NCX is a ____ (major/minor) contributor of Ca influx

A

minor

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5
Q

when might there be reduced removal of Na from the cells and entry of Ca by the NCX?

A

if the patient is taking a diuretic that depletes the body’s Na

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6
Q

when diuretics indirectly affect the NCX does it cause a vasodilator or vasoconstrictive effect?

A

vasodilator

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7
Q

the guanylyl cyclase pathway promotes vasodilation by increasing _____ of myosin, which releases the contractile stste of the smooth muscle cell

A

dephosphorylation

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8
Q

organic nitrates like ____ act in this pathway to cause vasodilation in patients with angina

A

nitroglycerin

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9
Q

what drug class does prazosin belong to?

A

alpha 1 adrenergic receptor antagonist (antihypertensive)

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10
Q

what is the MOA of alpha-1 antagonists like prazosin?

A

competes for binding to the A1 receptor and prevents endogenous action of NE secreted by sympathetic neurons and results in less Ca for contraction

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11
Q

activation of the alpha 1 receptor causes a _____coupled signalling cascade

A

Gq

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12
Q

a rise in intracellular Ca results in activation of mysoin ____

A

light chain kinase

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13
Q

while some Ca may come in by the NCX, most of the Ca enters through _____ channels

A

L-type voltage gated Ca channels

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14
Q

if we can block Ca channels, there will be less calcium ____ activation and a reduction in myosin _____ activity

A

calmodulin; light chain kinase

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15
Q

what are the 2 types of Ca channel blockers?

A
  1. dihydropyridine (DHP)

2. non-dihydropyridine

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16
Q

what class of drug does nifedipine belong to?

A

dihydropyridine type Ca channel blockers (vasodilator; antihypertensive)

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17
Q

what class of drug does diltiazem belong to?

A

non-dihydropyridine type Ca channel blocker (vasodilator; antihypertensive)

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18
Q

what is the clinical distinction between DHP and non-DHP Ca channel blockers?

A

DHPs are only effective in blocking Ca channels in smooth muscle cells, but not those in cardiac muscle cells, but non-DHP act in both

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19
Q

blocking Ca channels in cardiac muscle cells generally causes a _______ (increase/decrease) in the activity of these cells

A

decrease

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20
Q

why are non-DHPs like diltiaem not typically used?

A

they can block ca channels in the heart wich reduces activity of heart cells

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21
Q

what are some of the common ADRs of vasodilators?

A

orthostatic hypotension, dizziness, headaches, bradycardia, cardiac suppression, urinary incontinence

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22
Q

what is the severity of hypotension, dizziness and headaches ADRs of vasodilators?

A

usually not serious, typically resolves over time, but if it doesnt resolve some ptaintes may need dose adjustments

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23
Q

bradycardia & cardiac suppression as ADRs are typically seen with what types of vasodilators?

A

non-DHPs like diltiazem

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24
Q

urinary incontinence as an ADR is typically not severe and is typically caused by what class of vasodilators?

A

A1 andronergic blockers also acting in other smooth muscle like prazosin

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25
Q

t/f prozosin can be used for the treatment of urinary retnetion

A

t

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26
Q

t/f vasodilators alone are typically not enough to manage hypertension

A

t

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27
Q

when a drop in BP is sensed, the _____ nervous system is activated

A

sympathetic

28
Q

stimulation of B____ receptors in cardiac tissues increases heart rate and contractility, and cardiac output, resulting in increased BP

A

1

29
Q

why would it not make much sense to use nifedipine and prazosin togther?

A

they both act on smooth muscle to reduce contractility and it is typically better to choose agents that have differing MOAs

30
Q

why would it not make sense to use an ACE inhibitor and ARB togther?

A

bc they act on the same pathway, and we typically want to diversify to get bettwer efficacy

31
Q

what is angina?

A

a condition where narrowing of the coronary vessesl causes reduced blood flow and reduced O2

32
Q

angina typically presents as ___

A

chest pain or pressure upon excretion of exercise

33
Q

angina that worsens with exercise is called ___

A

effort angina

34
Q

what is the main management for angina?

A

to balance out O2 supply and demand, which will help to reduce the symptoms ; lowering BP can also help

35
Q

vasodilators increase O2 ____

A

supply

36
Q

B blockers decrease O2 _____

A

demand

37
Q

organic nitrates cause ____ to ____increase/decrease O2 supply

A

vasodilation; increase

38
Q

what agents can be used to reduce cardiac output to reduce O2 demand?

A

B blockers and non-NHPs like diltiazem

39
Q

organic nitrates act by increasing ____ in the vascular smooth muscle cells

A

nitric oxide

40
Q

nitric oxide is normally produced by ____ cells surrounding vascular smooth muscle cells in BV

A

endothelial

41
Q

when nitric oxide is made, it diffuses into the vascular smooth muscle cells where it increases the activity of ____, which promotes more ____

A

guanylase cyclase; cyclic GMP

42
Q

cyclic GMP activates ____ that dephosphorylate myosin light chains, causing muscle relaxation

A

phosphatases

43
Q

endogenously, nitric oxide has a very _____ (long/short) half life

A

short

44
Q

due to its short t1/2, NO is not an effective therapeutic strategy on its own, but we can administer drugs that produce NO once they are inside these cells, these agents are called ____

A

nitric oxide donors

45
Q

____ are one class of nitric oxide donors that can be used to achieve vasodilation in angina

A

organic nitrates

46
Q

____ is one of the more familiar nitrate agents used clinically

A

nitroglycerin

47
Q

nitroglycerin is metabolized in vascular smooth muscle cells by _____ and other enzymes to make NO

A

glutathione S-transferase

48
Q

organic nitrates are readily metabolized in the ____, giving them _____ (high/low) oral bioavailability

A

liver; low

49
Q

what are the typical administration routes of nitroglycerin?

A

parenteral: sublingual, transdermal are most common

50
Q

sublingual nitroglycerin is for ______ (acute PRN or chronic prophylactic) use

A

acute PRN

51
Q

transdermal nitroglycerin is for ______ (acute PRN or chronic prophylactic) use

A

chronic prophylactic

52
Q

what type of nitroglycerin should a patient with effort angina take?

A

sublingual

53
Q

what type of nitroglycerin should a patient with angina at rest take?

A

transdermal

54
Q

nitrates cause a ______(reduced/increased) preload in the heart and _____ (reduces/increases) the after load

A

reduced;reduces

55
Q

what is preload?

A

the filling pressure of the heart

56
Q

what is after load?

A

the pressure the heart needs to pump against

57
Q

dilation of ____ arteries reduces the after load

A

coronary

58
Q

dilation of _____ reduces preload

A

veins

59
Q

nitroglycerin increases O2 ____ and decreases O2 ____

A

supply; demand

60
Q

when using nitrates, one of the ADRs (aside from orthostatic hypotension, headache, dizziness) is a compensatory increase in ______

A

heart rate (which can increase BP)

61
Q

wrt to the ADR of compensatory tachycardia, which patients are more likely to require an additional antihypertensive to manage this?

A

those taking it chronically (usually goes away for PRN users)

62
Q

_____ develops with continual nitrate exposure

A

tolerance

63
Q

why does nitrate tolerance happen?

A

saturation of the metabolic pathways required to activate organic nitrate, causing less NO production and reduced vasodilation

64
Q

is a patient has developed nitrate tolerance, will changing the dose restore the effect?

A

no

65
Q

how can the development of nitrate tolerance be minimized?

A

have chronic use patients schedule a nitrate-free period , usually overnight for 8 hrs, which will promote restoration of the enzymes and substrates needed for the metabolic pathways in the morning

66
Q

organic nitrates are dangerous when combined with what type of drug?

A

erectile dysfunction drugs like sildenafil

67
Q

why is it dangerous to combine erectile dysfunction drugs like sildenafil with organic nitrates?

A

sildenafil inhibits the breakdown cyclic GMP by phosphodiesterase, which promotes vasodilation and blood flow to peripheral areas, when combined with nitrates, this causes a very large increase in cyclic GMP and a very large hypotensive effect that can be extremely dangerous and even fatal

Pharmacology (49 decks)

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