4.4 Antiarrhythmic Drugs Flashcards

1
Q

Which generates slower + shorter impulses; SAN or Purkinje Fibers?

A

SAN

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2
Q

Which contracts 1st, atria or ventricles?

A

Atria contracts before the ventricles, causing the characteristic rhythm of the heart

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3
Q

Arrhythmia is an abnormal cardiac rhythm from…

A
  • Abnormal impulse …
    • Generation
    • Conduction
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4
Q

What is Atrial Fibrillation?

A

Irregular heartbeat

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5
Q

What are the Class I Antiarrhythmic Drugs?

A

Sodium Channel Blockers

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6
Q

What are the Class II Antiarrhythmic Drugs?

A

β-adrenergic receptor blockers

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7
Q

What are the Class III Antiarrhythmic Drugs?

A

Potassium Channel Blockers

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8
Q

What are the Class IV Antiarrhythmic Drugs?

A

Calcium Channel Blockers

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9
Q

What are the Unclassified Antiarrhythmic Drugs?

A

Adenosine, Magnesium, Potassium

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10
Q

What class of antiarrhythmic drugs preferentially bind to the activated sodium channels?

A

Class 1A + 1C

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11
Q

What class of antiarrhythmic drugs preferentially bind to the inactivated sodium channels?

A

Class 1B

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12
Q

What are the 3 Class IA drugs?

A
  • Procainamide
  • Disopyramide
  • Quinidine
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13
Q

What are the cardiac effects of Class IA antiarrhythmic drugs? (3)

A
  • Slow 0 phase of AP
    • When MP is actively rising
  • Slow impulse conduction
  • Prolong action of potential duration
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14
Q

What is procasinamide metabolized to?

A

N-acetylprocainamide (NAPA)

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15
Q

Both NAPA + dysopyramide are eliminated by the …

A

kidneys

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16
Q

What is the therapeutic use of Procainamide (Class IA)?

A

Atrial + Ventricular Arrhythmias

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17
Q

What is the therapeutic use of Disopyramide (Class IA)?

A

Ventricular Arrhythmia (USA)

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18
Q

What is the toxicity associated with Procainamide (Class IA)? (3)

A
  • Hypotension due to ganglion-blocking
  • Excessive cardiac effects (torsadogenesis)
  • Lupus-related effects (erythematosus)
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19
Q

What is the toxicity associated with Disopyramide (Class IA)? (3)

A
  • Negative iontropic effects on the heart
  • May precipitate heart failure
  • Atropine-like activitives
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20
Q

What are the Class IB antiarrhythmic drugs? (2)

A
  • Lidocaine (LA)
  • Mexiletine
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21
Q

What are the cardiac effects of Class IB antiarrhythmic drugs? (2)

A
  • Bind to inactivated state of sodium channels
    • Prolongs the inactiviety of Na channels
  • Depresses conduction in depolarized cells
    • Slows down the rate at which impulses are being initiated
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22
Q

Which Class IB antiarrhythmic drug has the longest half life?

A
  • Mexiletine = 8-20 hrs
    • Orally administered
  • Lidocaine = 1-2 hrs
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23
Q

Where are the Class IB antiarrhythmic drugs metabolized?

A

Liver

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24
Q

What is the therapeutic use of the Class IB drugs?

A

Ventricular Tachycardia

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25
Q

What is the therapeutic use of Mexiletine (Class IB)?

A

Pain release for diabetic neurology

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26
Q

Which class of sodium channel blockers is the least toxic?

A

Class IB

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27
Q

What is the toxicity associated with Class IB sodium channel blockers? (2)

A
  • Large doses may cause hypotension
  • LA neurologic effects
28
Q

What are the Class IC sodium channel blockers? (2)

A
  • Flecainide
  • Propafenone
29
Q

What are the cardiac effects of Class IC sodium channel blockers? (2)

A
  • Blocks sodium channels with slow kinetics
  • Blocks potassium channels with slow kinetics
30
Q

How are Class IC drugs administered?

A

orally, and well absorbed

31
Q

How are Class IC drugs eliminated and metabobilized?

A
  • Eliminated by liver
  • Metabolized in kidneys
32
Q

What are the therapeutic uses of Class IC drugs? (2)

A
  • Supraventricular arrhythmias
  • Premature ventricular conductions
33
Q

What is the toxicity associated with Class IC drugs?

A

Severe exacerbation of arrhythmias in preexisiting conditions

34
Q

What is the toxicity associated with Propafenone (Class IC)?

A

Constipation

35
Q

What are the Class II antiarrhytmic drugs?

A
  • Propranolol
  • Esmolol
  • Sotalol
36
Q

What are the Class II nonselective β-blockers?

A
  • Propranolol
  • Sotalol
37
Q

What Class II drug is β1-selective?

A

Esmolol

38
Q

What antiarrhythmic drugs are contraindicated in pts with Asthma?

A

Class III = non-selective β-blockers (propranolol, sotalol)

These pts require β2 stimulation

39
Q

What are the cardiac effects of Class II drugs?

A

Slows AP duration

  • Propranolol - also slows impulse conduction
40
Q

What is the therapeutic use of Esmolol (Class II)?

A

Intraoperative acute arrhytmias

41
Q

What are the Class III antiarhythmic drugs? (4)

A
  • Amiodarone
  • Dronedarone
  • Dofetilide
  • Ibutilide
42
Q

What are the cardiac effects of Amiodarone (Class III) antiarrhythmic drugs? (3)

A
  • Shows complex effects (class I, II, III, IV actions)
  • Prolongs AP duration
  • Prolongs duration of refractory period
43
Q

How is Amiodarone (class III) administered?

A

Oral + IV

44
Q

How is amiodarone (Class III) metabolized?

A

Liver (CYP3A4)

45
Q

What are the therapeutic uses of Amiodarone (Class III)? (2)

A
  • Recurrent ventricular tachycardia
  • Atrial fibrillation
46
Q

What drug is structurally related to thyroxine, and inhibits conversion of T4 to T3?

A

Amiodarone (Class III)

47
Q

What is the toxicity associated with Amiodarone (Class III)? (3)

A
  • Bradycardia + heart block
  • Pulmonary toxicity (fibrosis)
  • Abnormal liver function (b/c extensive metab) + hepatitis
48
Q

What Class III drug is an amidarone analog, without iodine in it?

A

Dronedarone

49
Q

What are the cardiac effects of Dronedarone (Class III)? (2)

A
  • Prolongs AP duration
  • Weak β-blocking activity
50
Q

Which Class III drug has increased absorption by 2-3 fold when taken with food?

A

Dronedarone

51
Q

What is the therapeutic use of Dronedarone (Class III)?

A

Atrial Fibrillation

52
Q

What is the toxicity associated with Dronedarone (Class III)?

A

Abnormal liver function + hepatitis

53
Q

What Class III drug is only administered orally, with 100% bioavailability?

A

Dofetilide

54
Q

What is the toxicity associated with Dofetilide (Class III)?

A

Ventricular pro-arrhythmias

55
Q

What Class III drug is administered only by IV?

A

Ibutilide

56
Q

What is the therapeutic use for Ibutilide, besides the typical use of Class III drugs to atrial fibrillation?

A

Atrial flutter

57
Q

What is the toxicity associated with Ibutilide (Class III)?

A

Excessive QT prolongation + torsadogenesis

58
Q

What are the Class IV antiarrhythmic drugs? (2)

A
  • Verapamil
  • Diltiazem
59
Q

What are the cardiac effects of Class IV drugs?

A
  • Prolongs effective refractory period
  • Supresses early + delayed afterdepolarization
60
Q

What is Verapamil (Class IV) useful in treating?

A

Supraventricular tachycardia

61
Q

Which Class IV drug is available in Intraventricular form?

A

Diltiazem

62
Q

What are the cardiac effects of Adenosine? (4)

A
  • Increases potassium conductance
  • Inhibits calcium current
  • Hyperpolarization
  • Suppression of calcium-dependent AP
63
Q

What is the effect of Adenosine at a high bolus dose?

A

Inhibits AV node conduction

64
Q

What is the 1/2 life of Adenosine?

A

1/2 life in the blood = 10 seconds

Not good for long term use

65
Q

What is the drug of choice for supraventricular tachycardia?

A

Adenosine

Verapamil is also used for SVT

66
Q

What is the toxicity/symptoms associated with Adenosine? (3)

A
  • Flushing
  • Shortness of breath
  • Chest burning
67
Q

What drugs are at risk for drug-drug interactions with Antiarrhytmic drugs? (2)

A
  • Catecholamines
  • Antiarrhythmic drugs