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Pharmacology-J > Antiarrhythmics > Flashcards

Antiarrhythmics Flashcards

1
Q

Class IA antiarrhythmic drugs

A
  1. Quinidine
  2. Procainamide
  3. Disopyramide
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2
Q

Class IA antiarrhythmic mechanism of action

A
  1. Block Na+ and K+ channels (phase 0 and phase 3)
  2. Intermediate dissociation rate (secs)
  3. Inc QRS and QT intervals
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3
Q

Class IB antiarrhythmic mechanism of action

A
  1. Block Na+ channels
  2. Rapid dissociation rate (<1 sec)
  3. Shortened QT interval
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4
Q

Class I antiarrhythmics block phase _

A

0

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5
Q

Class IC antiarrhythmic mechanism of action

A
  1. Block Na+ channels
  2. Slow dissociation rate (>10 sec)
  3. Inc QRS duration
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6
Q

Side effects with procainamide

A
  • Rash, myalgia, vasculitis, Raynauds
  • Fever, hypotension, bradycardia
  • QT prolongation, Torsades de Pointes
  • Drug induced lupus (oral)
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7
Q

Uses for procainamide

A

IV only

  • Sustained vtach
  • unmasking brugada syndrome
  • AF in WPW
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8
Q

Class IB drugs

A
  1. lidocaine (IV)

2. mexiletine (oral)

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9
Q

Class ___ antiarrhythmics have increased potency in ischemic tissue

A

IB

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10
Q

Indications for class IB antiarrhythmics

A
  1. Vtach
  2. Vfib
    * *not useful for atrial arrhythmias
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11
Q

Side effects of Class IB antiarrhythmics

A

Mainly CNS
lidocaine: visual disturbances, tremors, seizures, hallucinations, coma, asystole, hypotension, N/V
Mexiletine: GI: N/V/D, constipation, blurred vision, ataxia, HA, tremor, confusion

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12
Q

Class IC drugs

A

Flecainide

Propafenone

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13
Q

Indications for class IC antiarrhythmics

A
  1. Afib in patients without CAD or HF

2. SVT

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14
Q

Adverse effects of class IC antiarrhythmics

A

Flecainide: VT/VF in pts with CAD, aflutter, dizziness, dyspnea, HA, blurred vision, nausea, tremor, fatigue, HF exacerbation, AV block
Propafenone: unusual taste, dizziness, HA, nausea, fatigue, constipation, diarrhea, HF, blurred vision, bradycardia, palpitations, bronchospasms

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15
Q

Class II antiarrhythmic drugs

A

Beta blockers:

  1. Metoprolol
  2. Propranolol
  3. Esmolol
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16
Q

Mechanism of action of Class II antiarrhythmics

A
  • Reduction in intracellular cAMP concentration
  • Reduction of the funny current
  • Slows and limits Ca++ influx
  • Inc PR interval
  • Dec slope of phase 4 depolarization
  • Prolonged repolarization at AV node
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17
Q

Indications for class II antiarrhythmics

A
  • Treat/prevent supraventricular and ventricular arrhythmias
  • Afib/flutter: control ventricular rate
  • Paroxysmal SVTs: terminate and prevent ventricular arrhythmias
  • Ventricular arrhythmias: raise threshold for ventricular fibrillation in ischemic myocardium
  • Reduce ventricular arrhythmias and cardiac arrest after ACS and in pts with HF
  • Reduce DADs by reducing increases in Ca++ influx
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18
Q

Adverse effects of class II antiarrhythmics

A
  • fatigue
  • bronchospasm
  • hypotension
  • impotence
  • depression
  • HF exacerbation
  • masking of symptoms of hypoglycemia in DM
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19
Q

Mechanism of action of class III antiarrhythmics

A
  • Block K+ delayed rectifier current (phase 3)
  • prolonged repolarization period
  • prolonged QT interval
20
Q

Class III antiarrhythmic drugs

A
  1. Dronedarone
  2. Amiodarone
  3. Sotalol
  4. Ibutilide
  5. Dofetilide
21
Q

Mechanism of action of amiodarone

A
  • K+ channel blocker (class III), prolongs action potential duration/phase 3
  • Na+ channel blocker (class I), blocks inactivated Na+ channels, relatively rapid rate of recovery
  • L-type Ca++ blocker (class IV), slows sinus and AV node conduction
  • B1, B2, a1 receptor blocker (class II), slows sinus and AV node conduction
22
Q

True/false: amiodarone works best at high HRs

A

True

23
Q

Pharmacokinetics of amiodarone

A
  • Highly lipophilic (large volume of distribution)
  • Delayed onset of action (need loading dose 10g total)
  • T1/2 of 2months
  • Hepatic metabolism CYP3A4 and 2C8 to active metabolite
  • Inhibits CYP3A4, CYP2C9 and P-glycoprotein (drug interactions with digoxin, warfarin, statins)
24
Q

Contraindications for amiodarone

A
  • known hypersensitivity to amiodarone, including iodine
  • Cardiogenic shock
  • marked sinus bradycardia
  • 2nd or 3rd degree AV block w/out pacemaker
25
Q

Amiodarone black box warning

A
  • pulmonary toxicity (10-17%)
  • Liver injury
  • Worsening cardiac dysrhythmias
26
Q

Which drug is rarely prorhythmic?

A

Amiodarone

27
Q

Warnings for amiodarone

A
  • hypotension (IV)
  • bradycardia/AV block
  • Liver enzyme elevations
  • Proarrhythmia
  • Pulmonary disorders
  • Thyroid abnormalities
  • Surgery needs close monitoring
  • Acute photosensitivity/blue discoloration
  • CNS effects
28
Q

Mechanism of action class IV antiarrhythmics

A
  1. Non-dihydropyridine calcium channel blockers

2. State dependent inhibition of L-type Ca++ channels

29
Q

Class IV antiarrhythmic drugs

A

Verapamil
Diltiazem
IV and PO

30
Q

Indications for Class IV antiarrhythmics

A
  • supraventricular tachycarrhythmias
  • afutter/afib
  • SVTs
31
Q

Adverse effects of class IV antiarrhythmics

A

hypotension, bradycardia, AV block, negative inotropy

32
Q

Digoxin mechanism

A
  • enhances central and peripheral vagal tone (sensitization of baroreceptors, inc paraympathetic tone, prolongs AV node refractory and decreases SA node automaticity)
  • Inhibits Na/K ATPase pump (inc intracellular Ca++, Inc contractility and proarrhythmic potential)
33
Q

Indications for digoxin

A

-Afib/aflutter, control of ventricular rate (only reduces RESTING HR, good w/BB or CCB, HFrEF)

34
Q

Therapeutic window of digoxin

A

Narrow- 0.5-2.0 ng/ml (<1.0 in HF)

35
Q

Adverse effects of digoxin

A

GI, halo vision, malaise, bradycardia, AV block, vtach/vfib

36
Q

Mechanism of action for adenosine

A
  • Activates acetylcholine-sensitive K+ current in the atrium and sinus and AV nodes
  • hyperpolarization and suppression of calcium dependent APs
  • Inc ERP of AVN
  • Blocks conduction through the AV node
  • Terminates PSVTs
37
Q

Half life of adenosine

A

1-6 seconds

38
Q

Adverse effects of adenosine

A

Transient flushing, dyspnea, bronchospasm, chest pressure/fullness

39
Q

Class, MOA and limitation of Procainamide

A
  • Class Ia
  • Na+ and K+ channel blockers
  • Risk of Torsades de Pointes, possible inc risk mortality
40
Q

Class, MOA and limitation of lidocaine

A
  • Class Ib
  • Na+ blocker (fast kinetics)
  • No efficacy in atrial arrhythmias
41
Q

Class, MOA and limitation of Mexiletine

A
  • Class Ib
  • Na+ blocker (fast kinetics)
  • No efficacy in atrial arrhythmias
42
Q

Class, MOA and limitation of Flecainide

A
  • Class Ic
  • Na+ blocker (slow kinetics)
  • contraindicated in CAD and structural heart disease
43
Q

Class, MOA and limitation of B blockers

A
  • Class II
  • Beta adrenergic receptor competitive antagonist
  • Hypotension and bradycardia
44
Q

Class, MOA and limitation of Amidarone

A
  • Class III
  • Multichannel blocker
  • Extra-cardiac side effects
45
Q

Class, MOA and limitation of Dofetilide

A
  • Class III
  • K+ channel inhibition
  • Risk of Torsades de Pointes, dependent on renal clearance
46
Q

Class, MOA and limitation of Sotalol

A
  • Class III
  • K+ channel blocker
  • RIsk of Torsades de Pointes, dependent on renal clearance
47
Q

Class, MOA and limitation of DHCCB’s (verapamil, diltiazem)

A
  • Class IV
  • L-type Ca++ blocker
  • Hypotension and bradycardia

Pharmacology-J (3 decks)

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