4.4 Antiarrhythmic Drugs Flashcards
Which generates slower + shorter impulses; SAN or Purkinje Fibers?
SAN
Which contracts 1st, atria or ventricles?
Atria contracts before the ventricles, causing the characteristic rhythm of the heart
Arrhythmia is an abnormal cardiac rhythm from…
- Abnormal impulse …
- Generation
- Conduction
What is Atrial Fibrillation?
Irregular heartbeat
What are the Class I Antiarrhythmic Drugs?
Sodium Channel Blockers
What are the Class II Antiarrhythmic Drugs?
β-adrenergic receptor blockers
What are the Class III Antiarrhythmic Drugs?
Potassium Channel Blockers
What are the Class IV Antiarrhythmic Drugs?
Calcium Channel Blockers
What are the Unclassified Antiarrhythmic Drugs?
Adenosine, Magnesium, Potassium
What class of antiarrhythmic drugs preferentially bind to the activated sodium channels?
Class 1A + 1C
What class of antiarrhythmic drugs preferentially bind to the inactivated sodium channels?
Class 1B
What are the 3 Class IA drugs?
- Procainamide
- Disopyramide
- Quinidine
What are the cardiac effects of Class IA antiarrhythmic drugs? (3)
- Slow 0 phase of AP
- When MP is actively rising
- Slow impulse conduction
- Prolong action of potential duration
What is procasinamide metabolized to?
N-acetylprocainamide (NAPA)
Both NAPA + dysopyramide are eliminated by the …
kidneys
What is the therapeutic use of Procainamide (Class IA)?
Atrial + Ventricular Arrhythmias
What is the therapeutic use of Disopyramide (Class IA)?
Ventricular Arrhythmia (USA)
What is the toxicity associated with Procainamide (Class IA)? (3)
- Hypotension due to ganglion-blocking
- Excessive cardiac effects (torsadogenesis)
- Lupus-related effects (erythematosus)
What is the toxicity associated with Disopyramide (Class IA)? (3)
- Negative iontropic effects on the heart
- May precipitate heart failure
- Atropine-like activitives
What are the Class IB antiarrhythmic drugs? (2)
- Lidocaine (LA)
- Mexiletine
What are the cardiac effects of Class IB antiarrhythmic drugs? (2)
-
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
Which Class IB antiarrhythmic drug has the longest half life?
-
Mexiletine = 8-20 hrs
- Orally administered
- Lidocaine = 1-2 hrs
Where are the Class IB antiarrhythmic drugs metabolized?
Liver
What is the therapeutic use of the Class IB drugs?
Ventricular Tachycardia
What is the therapeutic use of Mexiletine (Class IB)?
Pain release for diabetic neurology
Which class of sodium channel blockers is the least toxic?
Class IB