Class IA Flashcards

1
Q

What three drugs do we need to know from class IA?

A
  • Procainamide
  • Quinidine
  • Disopyramide
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2
Q

What is the MOA for Procainamide?

A
  • Inc. AP duration
  • Inc. Effective Refractory Period
  • Inc. QT interval
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3
Q

What is the MOA for Quinidine?

A
  • Inc. AP duration
  • Inc. Effective Refractory Period
  • Inc. QT interval
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4
Q

What is the MOA for Disopyramide?

A
  • Inc. AP duration
  • Inc. Effective Refractory Period
  • Inc. QT interval
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5
Q

What are the cardiac effects of Class IA?

A
  • Slows upstroke of AP
  • Slows conduction of impulse
  • Prolongs QRS
  • Prolongs AP duration by blocking K+ channels
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6
Q

What are the extra cardiac effects of Procainamide?

A

Ganglionic blocking properties reduces peripheral vascular resistance –> hypotension

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7
Q

What are the extra cardiac effects of Quinidine?

A

Antimuscarinic Effects

Cinchonism (HA, dizziness, tinnitus)

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8
Q

What are the extra cardiac effects of Disopyramide?

A

Antimuscarinic Effects (ABCs - Anorexia, Blurred vision, Constipation/Confusion, Dry Mouth, Sedation/Stasis of urine)

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9
Q

What are the pharmacokinetics of Procainamide?

A
  • Metabolite (N-acetylprofainamide) has class III activity & is associated with torsades
  • Hepatic metabolism to NAPA, which is then excreted by the kidneys
  • Half life of NAPA is longer than Procainamide
  • Plasma Protein Binding = 15-20%
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10
Q

What are the pharmacokinetics of Quinidine?

A
  • Readily absorbed GI
  • Hepatic Metabolism
  • Renally excreted
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11
Q

What are the pharmacokinetics of Disopyramide?

A
  • Loading does not recommended (can precipitate heart failure)
  • Hepatic metabolism
  • Renally excreted
  • Plasma Protein Binding = 50-60%
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12
Q

What is the toxicity of Procainamide?

A
  • Excessive AP prolongation and QT duration can lead to Torsades and syncope
  • Long term can cause SLE like syndrome
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13
Q

What is the toxicity of Quinidine?

A

-Induction of Torsades

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14
Q

What is the toxicity of Disopyramide?

A
  • Induction of Torsades

- May precipitate torsades de novo or in those with preexisting depression of LV function

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15
Q

What is the therapeutic use of Procainamide?

A
  • Most Atrial and Ventricular Arrhythmias

- 2nd/3rd choice drug for sustained ventricular arrhythmias w/acute MI

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16
Q

What is the therapeutic use of Quinidine?

A

Rarely used due to toxicity

17
Q

What is the therapeutic use of Disopyramide?

A

-Only approved for ventricular arrhythmias