Antidysrhythmic Drugs



Antidysrhythmic Drugs







TERMS



  • □ bretylium (Bretylol)


  • □ diltiazem (Cardizem)


  • □ flecainide (Tambocor)


  • □ lidocaine (Xylocaine)


  • □ propranolol (Inderal)


  • □ quinidine (Quinaglute)



QUICK LOOK AT THE CHAPTER AHEAD

Antidysrhythmic drugs, also known antiarrhythmics, are indicated to prevent or treat dysrhythmias (arrhythmia). Dysrhythmias occur as a result of alterations in electrical impulses that regulate cardiac rhythm. It is important to note that antidysrhythmic drugs can also cause dysrhythmias or worsen existing ones. It is imperative that the nurse closely monitor clients during treatment.

The Vaughan Williams classification of antidysrhythmic drugs is a frequently used system based on the effect produced by a particular antidysrhythmic on the action potential. Four major groups of agents have been identified. Class I, also known as sodium channel blockers, is further broken down into Classes IA, IB, and IC, depending on their effects in phase 0, action potential duration, and effective refractory period. Class II drugs are beta-blockers that depress phase 4 depolarization. Class III potassium blockers prolong repolarization during phase 3. Class IV includes calcium channel blockers and depresses phase 4 depolarization and prolongs repolarization during phases 1 and 2.1









Table 40-1 Antidysrhythmic Drugs







































Prototype Drug

Related Drugs

Drug Classification


There is no prototype for this classification

moricizine (Ethmozine)

Class I: Sodium channel blocker


quinidine (Quinaglute)

disopyramide (Norpace) procainamide (Pronestyl)

Class IA


lidocaine (Xylocaine)

mexiletine (Mexitil) tocainide (Tonocard)

Class IB


flecainide (Tambocor)

propafenone (Rythmol)

Class IC


propranolol (Inderal)

acebutolol (Sectral) esmolol (Brevibloc) sotalol (Betapace), also a Class III drug

Class II: Beta-blockers


bretylium (Bretylol)

amiodarone (Cordarone) dofetilide (Tikosyn) ibutilide (Corvert)

Class III: Potassium channel blockers


diltiazem (Cardizem)

verapamil (Calan)

Class IV: Calcium channel blockers


There is no prototype for this classification

adenosine (Adenocard)

Unclassified antidysrhythmic



ANTIDYSRHYTHMIC DRUGS CLIENT TEACHING


All Antidysrhythmics



  • Take pulse and monitor rate and rhythm.


  • Report any worsening of symptoms of dysrhythmia, chest pain, edema, shortness of breath, dizziness, or sudden weight gain.


  • Carry medical identification.


  • Contact health care provider before taking herbals or other OTC medications.


  • Avoid caffeinated beverages as caffeine can cause an increase in arrhythmias.



  • Avoid driving or using heavy machinery if vision is blurred or you are dizzy.



image Take pulse and monitor rate and rhythm.



image Report any worsening of symptoms of dysrhythmia, chest pain, edema, shortness of breath, dizziness, or sudden weight gain.



image Carry medical identification.


Amiodarone (Cordarone)



  • Wear sunscreen and protective clothing and avoid sun exposure.


Procainamide (Pronestyl)



  • Notify health care provider if bleeding occurs or symptoms of lupus occur.


Disopyramide (Norpace) & dofetilide (Tikosyn)



  • Change positions slowly and avoid alcohol.


Quinidine (Quinaglute)



  • Report signs of bleeding, tinnitus, rash, and visual disturbances.


Quinidine (Quinaglute), disopyramide (Norpace), and procainamide (Pronestyl)



  • Should have regular dental check-ups due to antimuscarinic effects of quinidine and side effects of dry mouth from disopyramide and procainamide


ACTION


Class I: Sodium Channel Blockers


Moricizine (Ethmozine)



  • Exhibits characteristics of Class IA, IB, and IC. Blocks sodium channel in the myocardium, which prolongs PR interval and QRS duration, and suppresses prolonged automaticity


Class IA


Quinidine (Quinaglute)



  • Decreases myocardial excitability, slows conduction velocity, and has anticholinergic effects



  • Note: Procainadmide (Pronestyl) has weaker anticholinergic effects; disopyramide (Norpace) has stronger anticholinergic effects than quinidine.


Class IB


Lidocaine (Xylocaine)



  • Blocks sodium channels and reduces automaticity in the ventricles and His-Purkinje system, accelerates repolarization, and has little or no effect on the EKG


Class IC



  • Blocks sodium channels and decrease conduction velocity in the atria, ventricles, and His-Purkinje system


Class II: Beta-Blockers



  • Block or reduce sympathetic nervous system stimulation to the heart and heart’s conduction system, causing decreased heart rate, decreased myocardial contractility and automaticity, and delayed atrioventricular (AV) node conduction


Class III: Potassium Channel Blockers



  • Prolong the refractory period by prolonging the action potential, which delays repolarization. The drugs in this class affect the heart differently and are not interchangeable.


Class IV: Calcium Channel Blockers



  • Note: Calcium channel blockers are also discussed in Chapter 41.


  • Block calcium channels in the heart and have a negative dromotropic effect (decrease conduction rate)


Unclassified Antidysrhythmics


Adenosine (Adenocard)



  • Slows conduction time through the AV node and decreases automaticity in the sinoatrial (SA) node



USE


Class I: Sodium Channel Blockers


Moricizine (Ethmozine)



  • Life-threatening ventricular dysrhythmias


Class IA



  • Premature atrial contractions, atrial fibrillation, premature ventricular contractions, ventricular tachycardia, and Wolff-Parkinson-White syndrome


  • Note: Quinidine (Quinaglute) is an unlabeled use is for malaria treatment.


Class IB



  • Ventricular dysrhythmias


  • Lidocaine (Xylocaine) is also used as a local anesthetic


Class IC

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Oct 21, 2016 | Posted by in NURSING | Comments Off on Antidysrhythmic Drugs

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