Exam 3- Antiarrhythmics Flashcards
Quinidine
Class 1a
Lidocaine (xylocaine)
Class 1b
Propafenone (rythmol)
Class 1c
Beta-adrenergic antagonists
Class 2
Dronedarone (multaq)
Class 3
Verapamil (calan, isoptin)
Class 4
Procainamide
Class 1a
Mexiletine (mexitil)
Class 1b
Flecainide (tambocor)
Class 1c
Amiodarone (cardarone)
Class 3
Diltiazem (cardizem)
Class 4
Disopyramide (norpace)
Class 1a
Sotalol (betapace)
Class 3
Ibutilide (corvert)
Class 3
Dofetilide (tikosyn)
Class 3
Adenosine (adenocard)
Misc.
What does class 1 mostly block?
Phase 0 (Na)
What does 1a block?
Na and K
Dissociation rate for 1a?
Intermediate
Overall results of 1a?
Increase QRS and QT
What does 1b block?
Na
Dissociation rate for 1b?
Rapid (<1sec)
Overall result of 1b?
Decrease QT
What does 1c block?
Na
Dissociation rate for 1c?
Slow (>10sec)
Overall result of 1c?
Increase QRS
Indication for class 1b?
Ventricular tachycardia and ventricular fibrillation
Should you use 1b for atrial arrhythmias?
NO because not useful for anything above ventricles
Overall result from 1c?
Slow phase 0 (depolarization)
Dissociation rate for 1c?
Slow
2 Indications for class 1c?
Atrial fibrillation in patients without CAD or HF
SVTs
MOA of class 2?
Reduce intracellular cAMP:
- reduction of the funny current
- slows and limits Ca++ influx
Overall what does class 2 do?
Increase PR interval
Decrease slope of phase 4 depolarization
Prolong depolarization at AV node
What do beta blockers end in?
“olol”
Indications for class 2?
Treat/prevent Supra-ventricular and ventricular arrhythmias
7 adverse effects of beta blockers?
- Fatigue
- Bronchospasm
- Hypotension
- Impotence
- Depression
- Aggravation of HF
- Masking of symptoms of hypoglycemia in DM
MOA of class 3?
Block K+ delayed rectifier current
Overall effect of class 3?
Prolong redepolarization period (QT interval)
Major side effects to class 3?
Torsade de pointes
Bradycardia
Why is amiodarone considered a big gun?
- Na channel blocker (class 1)
- Beta and alpha 1 blocker (class 2)
- K channel blocker (class 3)
- L type Ca channel blocker (class 4)
When does amiodarone work best?
High heart rate
3 unusual pharmacokinetics with amiodarone:
- Delayed onset
- Loading dose required
- T1/2 of ~2months
Where is amiodarone metabolized?
Liver
What 3 other drugs have interactions with amiodarone?
Digoxin
Warfarin
Statins
4 contraindications for amiodarone:
- Known hypersensitivity (plus iodine)
- Cardiogenic shock
- Sinus bradycardia
- 2nd or 3rd degree AV block
What is the only thing that amiodarone does not affect?
Kidneys
MOA of class 3:
Non-dihydropyridine Ca++ channel blockers
Overall what does class 4 do?
Inhibition of l-type Ca channels that increase PR interval and ERP
- slow rise of AP
- prolonged repolarization at AV node
Indications for class 4:
Supraventricular tachyarrhythmias
- atrial flutter/fibrillation
- SVTs
4 adverse effects of class 4:
Hypotension
Bradycardia
AV block
Negative inotropy
What does digoxin do to central and peripheral vagal tone?
Enhance them
MOA of digoxin:
Inhibits Na/K-ATPase pump
- increase Ca
- increase contractility and proarrhythmic potential
Indications for digoxin:
Atrial flutter/fibrillation - control of ventricular rate
6 toxicity of digoxin:
- GI upset
- Altered color perception (halo vision)
- Malaise
- Bradycardia
- AV block
- Ventricular tachycardia/fibrillation
What does adenosine do?
Activates ACh-sensitive K current in atria and sinus and AV bodes
-hyperpolarization and suppression of Ca-dependent APs
What is the goal for adenosine?
Produce a complete AV block for a couple of seconds
What does adenosine terminate?
PSVTs (reentry involving AVN)
MOA of class 1a:
Inhibit Na
Inhibit K
-intermediate
MOA of 1b:
Inhibit Na
-fast
MOA of 1c:
Inhibit Na
-slow
MOA of class 2:
Beta adrenergic receptor competitive antagonist
MOA of class 3:
Multichannel blocker
Inhibit K
MOA of class 4:
Inhibit Ca L-type
Limitations for class 1a:
Risk of torsades de pointes, associated with possible increased mortality
Limitations for class 1b:
No efficacy in atrial arrhythmias
Limitations for class 1c:
Contraindicated in CAD and HF
Limitations for class 2:
Hypotension and bradycardia
Limitations for class 3:
Extra-cardiac side effects:
Risk of torsades de pointes, dependent on renal clearance
Limitations for class 4:
Hypotension and bradycardia