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Cardiology > Lecture 2: Drugs acting on the ANS > Flashcards

Lecture 2: Drugs acting on the ANS Flashcards

1
Q

If a tissue is innervated by only one branch of the ANS, which one will it be?

A

Sympathetic

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2
Q

Four transmitters of the ANS

A

ACh, NE, DA, Epi

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3
Q

Where is DA released?

A

By sympathetic fibers that innervate the renal vasculature and some other vessels beds

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4
Q

What nAChR receptor subtype is located at the ANS ganglia?

A

Nn

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5
Q

Besides nAChR what other cholinergic receptor class is found in the ANS?

A

Muscarinic

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6
Q

Do current drugs distinguish between muscarinic subtypes?

A

No

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7
Q

What NE receptor is postsynaptic? Excitatory or inhibitory?

A

Alpha-1; excitatory

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8
Q

Describe alpha-2 receptors

A

Presynaptic inhibitory autoreceptors (decrease Ca2+ currents)

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9
Q

All beta-adrenergic receptors…

A

Couple to Gs and increase cyclic AMP

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10
Q

More beta-1 > beta-2 in…

A

Heart, juxtaglomerular cells

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11
Q

More beta-2 > beta-1 in…

A

Bronchial smooth muscle, arterioles

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12
Q

D1 receptors couple to…and mediate…

A

Gs; vasodilation (prominent in renal vasculature)

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13
Q

D2 receptors couple to…and mediate…

A

Gi/Go; autoreceptors on terminals of dopaminergic neurons –> inhibit release

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14
Q

Alpha-1 vaso…; beta-2 vaso…Alpha-1 are widely/not widely expressed. How about beta-2?

A

Constrict; dilate; widely; beta-2 expression varies, but is greater in coronary and skeletal muscle arterioles

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15
Q

Describe sympathetic effects on vasculature (3). What happens renaly?

A

Increased TPR, decreased venous capacitance, redistribution of blood flow (away from alpha-1 beds and toward beta-2 beds); renal blood flow maintained due to D1 receptors

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16
Q

Describe receptor distribution and sympathetic effects on heart (ventricles vs atria)

A

Ventricles: beta-1 –> positive inotropy, lusitropy; Atria: beta-1 plus beta-2 (particularly at nodes) –> positive chronotropy, dromotropy

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17
Q

Lusitropy is…dromotropy is…

A

Relaxation rate; Conduction rate

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18
Q

Sympathomimetic drugs

A

Mimic effects of sympathetic transmitters

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19
Q

Sympatholytic drugs

A

Block normal sympathetic transmission

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20
Q

Epinephrine activates…duration of action?

A

All alpha and beta receptors; 1-2 minutes

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21
Q

At usual doses, Epi does what to mean BP?

A

Increase due to alpha-1 mediated vasoconstriction over beta-2 mediated vasodilation

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22
Q

How does Epi affect coronoary and skeletal perfusion? How about cerebral aterioles?

A

Increased; cerebral arterioles show little change in tone but increased resistance elsewhere –> increased blood flow

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23
Q

Describe low doses of Epi

A

Epi is more potent at β2 receptors than at α1 receptors, so will show decreased BP

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24
Q

How does Epi affect the heart? (4 and final effect)

A

Positive chronotropy, dromotropy, inotropy, lusitropy –> increased CO

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25
Q

Uses of Epi (5)

A

Cardiac arrest to restore rhythym, inotropic support (weakening ventricles), acute severe asthma, to restrict local anesthetic to site of injection, to relieve hypersensitivity reactions (anaphylaxis)

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26
Q

What is the MAIN way NE is different? What is the effect?

A

Alpha-1, beta-1 agonist but NOT beta-2 agonist; increase in BP more than Epi

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27
Q

Direct effects on the heart of NE…what happens next? How does this impact the inotropic effect?

A

Similar to Epi via beta-1 activation; powerful vagal reflex which DECREASES HR; inotropic effect intact because LITTLE VAGAL INPUT TO VENTRICLES

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28
Q

T/F: NE causes positive inotropic effect?

A

True

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29
Q

Uses of NE? (1)

A

Shock (cardiogeic, septic, hypovolemic)

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30
Q

Adverse effects of NE? (3)

A

Severe hypertension, risk of reduced renal flow, necrosis of tissue at site of injection

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31
Q

Isoproterenol is the prototypical…

A

Beta-receptor agonist

32
Q

What are the heart effects of isoproterenol? What are the primary uses and AEs?

A

Positive chronotropic and inotropic activity (large increase in HR, since the direct effect and reflex [↓ vagal tone] are in the same direction); treat bradycardia and some arrhythmias; palpitations, tachycardia, cardiac ischemia, flushing

33
Q

Isoproterenol does what to CO, MAP?

A

Increases; decreases

34
Q

Describe dobutamine

A

Selective beta-1 agonist; positive inotropic and chronotropic effects

35
Q

Which effect of dobutamine is more significant?

A

Inotropic because beta-2 receptors play a significant role at the SA node

36
Q

Uses/AEs of dobutamine

A

ST tx of cardiac decompensation after cardiac surgery/CHF; May increase ventricular rate in pts w/ Afib, also can cause ectopic ventricular activity

37
Q

Dopamine is an agonist at…Important why?

A

D1 > beta-1 > alpha; varying doses affects various receptors

38
Q

DA effect on BP

A

Hypotensive

39
Q

Low DA dose

A

Increased renal blood flow and urine output

40
Q

Intermediate DA dose. What happens to TPR?

A

Increased renal blood flow + cardiac effects (beta-1); no change in TPR

41
Q

High DA dose

A

Vasoconstriction (due to alpha involvement now); increased BP, but kidney perfusion spared

42
Q

Uses/AEs of DA

A

Treatment of cardiogenic shock (high dose); especially in oliguric patients with low or normal peripheral resistance, heart block that doesn’t respond to atropine or pacing, symptomatic bradycardia; tachycardia, anginal pain, hypotension, nausea, vomiting

43
Q

Fenoldopam is a…

A

Selective agonist at D1 receptors (peripheral and renal vessels)

44
Q

Uses/AEs of Fendolopam…Contraindication?

A

Treatment of severe hypertension; reflex tachycardia, headache, flushing; contraindicated in glaucoma

45
Q

Albuterol is a…

A

Selective agonist at beta-2 receptors

46
Q

Uses/AEs of Albuterol (including midl and moderate)

A

Bronchodilator for asthma, etc via relaxation of bronchial smooth muscle; mild to moderate: tachycardia, agitation, nausea, vomiting, hypokalemia, hyperglycemia; severe: Hypotension, dysrhythmias, seizures & acidosis

47
Q

Phenylephrine is a…What are it’s effects?

A

Alpha-agonist, slight selectivity for alpha-1; increases BP (especially diastolic), decreases HR

48
Q

Uses/AEs of Phenylephrine

A

Most common: decongestant, induce mydriasis and treat wide-angle gluacoma; Exacerbation of Raynaud’s, ↑BP, bronchoconstriction

49
Q

Clonidine is a…What does this mean?

A

Selective alpha-2 agonist (only sympatholytic adrenergic agonist because it DECREASES sympathetic outflow)

50
Q

Uses (3)/AEs (3) of Clonidine…

A

Management of hypertension/hypertensive crisis, pain management, opiate withdrawal; drowsiness, fatigue, xerostomia

51
Q

Tyramine is…

A

Not a drug! Normal metabolite of tyrosine metabolism –> indirect sympathomimetic

52
Q

Beta-adrenergic antagonists are called. Uses?

A

Beta blockers; hypertension, angina, arrhythmias, heart failure

53
Q

“Black box” warning of beta-blockers and two other important contraindication

A

Abrupt withdrawal can exacerbate angina; diabetes because it can induce hypoglycemia and asthma because it can lead to bronchoconstriction

54
Q

AEs of beta blockers (5)

A

Bradycardia, fatigue, CNS effects (insomnia, nightmares), worsening of Raynaud’s, erectile dysfunction

55
Q

What is a prototype non-selective beta-antagonist? Uses.

A

Propranolol; angina, arrhythmias, premature ventricular contraction, hypertension, MIs, pheochromocytoma (tumor that secretes NE)

56
Q

Metoprolol is a…

A

Beta-1 selective antagonist

57
Q

Uses (4)/Contraindications (3) of Metoprolol

A

Stable angina, congestive HF, HT, acute MI; sinus bradycardia, heart block, cardiogenic shock

58
Q

Pindolol is a…What does this mean?

A

Partial agonist of beta-1/beta-2 receptors; in absence of sympa stimulation, it is an agonist but an antagonist when sympa drive is high –> maintains beta receptor tone

59
Q

Uses (2) of Pindolol. What’s special about Pindolol?

A

Hypertension, angina; no black box warning

60
Q

Carvedilol is a…

A

Beta blocker (beta-1 and beta-2) plus alpha-1 receptor blocker

61
Q

Uses of Carvedilol (3). What’s special about Carvedilol (2)?

A

Heart failure, angina, HT; improves outcome in HF, preferred in diabetes (less effect on glucose metabolism than most beta blockers)

62
Q

Labetalol is a…

A

Mixed: antagonist at beta-1 and alpha-1 receptors = vasodilatory;
Partial agonist at beta-2 receptors

63
Q

Use of Labetalol

A

Hypertensive emergency, especially if excessive sympathetic activity

64
Q

Terazosin is a…Effect on BP?

A

Alpha blocker with similar alpha-1 and alpha-2 affinities; hypotensive

65
Q

Use of Terazosin. What population is this medication preferred for?

A

HT, preferred over beta-blockers in diabetes

66
Q

Does vagal activity affect vascular tone?

A

NO! Few vessels are parasympathetically innervated

67
Q

Parasympathetic effects on the heart (SA node, AV node, atrial muscle)

A

Major effects are on the atria; SA node: negative chronotropy (reduced automaticity); AV node: negative dromotropy (slowed conduction); atrial muscle: reduced contractility

68
Q

Two classes of drugs acting on parasympathetic branch

A

Parasympathomimetic (mimic ACh) and parasympatholytic (anticholinergic)

69
Q

Acetylcholine is a…What does IV adminstration lead to? Uses?

A

Full agonist at all muscarnic and nicotinic receptors; small dose causes transient drop in BP and reflex tachycardia, large dose affects heart (slows HR); used in eye surgery to induce miosis

70
Q

Bethanechol is a…

A

Muscarinic agonist

71
Q

Uses (2)/AEs of Bethanechol

A

Urinary retention, gastroesophageal reflux; hyptension/tachycardia (peripheral) and effects of excessive parasympa activity (ab cramping, bronchial constriction, salivation…)

72
Q

Neostigmine and Physostigmine are…

A

Cholinesterase inhibitors (carbamates)

73
Q

Uses/AEs of Neostigmine (3)

A

Myasthenia gravis, NM block, urinary retention

74
Q

Atropine and scopolamine are…

A

Muscarinic receptor antagonists

75
Q

Uses of Atropine…(3)

A

Sinus bradycardia, A-V block, to reduce parasympathetic function (inhibit salivation, GI spasms, etc)

76
Q

Ipratropium is a…why is it special?

A

Muscarinic antagonist that is inhaled only

77
Q

Uses of Ipratropium…(3)

A

Acute asthma, bronchospasm w/ COPD, short-term relief of rhinorrhea

Cardiology (22 decks)

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