Antiarrhythmia drugs Flashcards Preview

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Flashcards in Antiarrhythmia drugs Deck (17)
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1
Q

Class 1A Na+ channel blockers

A
  • Quinidine, procainamide, disopyramide.
  • Increase threshold for AP firing.
  • Decrease Vmax (lowers rate of upstroke).
  • Increase ERP.

Indirect effects:

  1. Blocks K+ channels (potential for EADs).
  2. Vagolytic effect (can increase AV conduction - would need to give Digoxin).

Uses: atrial flutter; a fib; prevent v tach and v fib. Contraindicated in patients with LQTS.

2
Q
A

Class 1A (quinidine, procainamide, disopyramide)

3
Q

Lidocaine

A
  • Class: 1B
  • Blocks Na+ channels in a use-dependent manner.
  • Increase AP threshold.
  • Decreases AP duration and ERP.

Use: V tach; digitalis-induced arrhythmias, safe for patients with LQTS.

4
Q
A

Class IB (lidocaine)

5
Q

Flecainide

A
  • Class: 1C
  • Increase AP threshold.
  • Reduce Vmax.

Side effects: pro-arrhythmic.

Approved for use in life-threatening situations. Really potent. LQTS3.CPVT.

6
Q
A

Class 1C (flecainide)

7
Q

B-blockers

A

Class II

Propranolol (long-acting), Esmolol (short-acting).

Slow the rate of diastolic depolarization (prolong PR interval). Do not prolong repolarization (safe for LQTS).

Used for all atrial arrhythmias, v tach and v fib.

8
Q
A

Class II (b-blockers)

9
Q

K+ channel blockers

A

Amiodarone, Sotalol, Dofetilide

Block K+ channels; prolong AP repolarization. Increased ERP. Reverse use-dependence.

Most common target is IKr (hERG channel).

10
Q
A

Class III (K+ channel blockers)

11
Q

Amiodarone

A

Class III (K+ channel blocker)

  • Blocks both IKr, IKs.
  • Modest Na+ channel blocker
  • Modest Ca++ channel blocker
  • Modest B-blocker

Effective against v tach and v fib. Prophylaxis of a fib or flutter.

Not associated with TdP, but yes with hypothyroidism. *Pulmonary toxicity.

12
Q

Sotalol

A

Major action is blocking IKr. Also has B blocking actions.

Most serious SE: TdP.

Effective against V tach, v fib, A tach and A Fib.

Administer with caution in conjuction with drugs that prolong the QT interval.

Renal clearance.

13
Q

Dofetilide

A

Blocks IKr.

SEs: triggered arrhythmias, TdP.

Most often used for Afib and atrial flutter.

Drugs that interfere with renal secretion system are contraindicated (increase chance of TdP).

14
Q

Ca++ channel blockers

A

Class IV (non-dihydropyridines: benzothiazepines, phenylalkylamines)

Act primarily on SA & AV node to slow the rate of depolarization. Increase nodal cell refractory period; increase threshold for AP firing in nodal cells.

Used primarily for paroxysmal SVT.

SEs: bradycardia, negative inotropic effect, hypotension.

Renal excretion.

15
Q
A

Class IV (Ca++ channel blockers)

16
Q

Adenosine

A

Very rapidly activates K+ channels to slow phase 4 depolarization at AV node.

Slows AV conduction and heart rate.

17
Q

Digoxin

A

Enhances vagal parasympathetic activity to slow conduction at the AV node.

Used for Afib and SVT to control ventricular response rate.