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Drugs for Arrhythmias. A. Pathophysiology of arrhythmias. Arrhythmias are a group of conditions in which the muscle contraction of the heart is irregular, and they occur in both healthy and diseased hearts. .

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A pathophysiology of arrhythmias
A. Pathophysiology of arrhythmias

  • Arrhythmias are a group of conditions in which the muscle contraction of the heart is irregular, and they occur in both healthy and diseased hearts.



B arrhythmia therapy
B. Arrhythmia therapy conditions: CAD, HT, and MI.

  • Antiarrhythmic drugs do not cure the underlying causes of an arrhythmia. Instead, they attempt to restore the normal cardiac rhythm.



1 class i antiarrhythmic drugs na 1 channel blockers
1. Class I antiarrhythmic drugs (Na potential that they affect.1+ channel blockers)

  • This class of drugs reduces the excitability of the heart by slowing the spread of impulse conduction across the heart.




Phase 4: The resting membrane potential, when the cell is not being stimulated (represented by baseline on the ECG).


Phase 0: This is the rapid depolarization phase and occurs with the opening of the Na1+ channels and the rapid influx of Na1+ into the cell.


Phase 1: This phase of the action potential occurs with the closure of the Na1+ channels. There is a transient net outward current due to the movement of K1+ and Cl1- ions. Phase 0 and 1 together correspond to the QRS complex of the ECG.


Phase 2: This is the plateau phase of the action potential and occurs because of the balanced inward movement of Ca2+ ions through calcium channels, and outward movement of K1+ ions through potassium channels. It corresponds to the ST segment of the ECG.


Phase 3: In this phase of the action potential, the K and occurs because of the balanced inward movement of Ca1+ channel is still open, allowing more K1+ to leave the cell, resulting in a net loss of positive charge, which causes the cell to repolarize. Phase 3 corresponds to the T wave of the ECG.


a. Class IA and occurs because of the balanced inward movement of CaThey slow the rate of rise of phase 0 and lengthen the action potential and are indicated for managing a variety of atrial and ventricular arrhythmias.



Quinidine gluconate 62 quinidine
quinidine gluconate subclass. (62% quinidine):

  • Quinidine is indicated for a wide variety of both atrial and ventricular arrhythmias. The off label use of this is the treatment of malaria.


  • Dosage: subclass.

  • IV: infuse at 16 mg/min until arrhythmia is resolved;

  • PO: 325 – 650 mg every 6 hours.


Quinidine sulfate 83 quinidine
quinidine sulfate subclass. (83% quinidine):

  • Dosage: PO: 400 – 600 mg every 2 – 3 hours until arrhythmia is resolved, for supraventricular tachycardia;






Procainamide procanbid promine pronestyl
procainamide variant of ventricular tachycardia), as can all class IA drugs(Procanbid, Promine, Pronestyl)

  • procainamide first approved for use in the United States in 1950, is indicated for a wide variety of both atrial and ventricular arrhythmias.





Disopyramide norpace rythmodan
disopyramide individuals experience lupus-like symptoms (rash, muscle pain). (Norpace, Rythmodan)

  • disopyramide is usually only used after quinidine and procainamide have been ruled out as possibilities. It is indicated for the treatment of ventricular tachycardia.




b. Class IB dry mouth, blurred vision, urinary retention, and constipation.They shorten the action potential and are indicated for the treatment of ventricular tachycardia and prevention of ventricular fibrillation



Lidocaine xylocaine
lidocaine dry mouth, blurred vision, urinary retention, and constipation.(Xylocaine)

  • lidocaine is indicated for the treatment of ventricular arrhythmias.

  • Dosage: IV: 50 – 100 mg bolus over 2 minutes, then 1 – 4 mg/min infusion



Mexiletine mexitil
mexiletine anaphylaxis, and seizures. It’s most common adverse effects include agitation, confusion, slurred speech, tremors and drowsiness. (Mexitil)

  • mexiletine (Mexitil) is structurally similar to lidocaine, except it can be administered orally.



  • Dosage mexiletine: a history of MI.

  • PO: 400 mg loading dose, then 200 mg more in 8 hours, then 200 – 400 mg every 8 hours


c. Class IC a history of MI. They have no effect on the length of the action potential, but reduce the rate of rise of phase 0. These drugs are indicated for the treatment of ventricular tachycardia and supraventricular tachycardia.



Flecainide tambocor
flecainide a history of MI. (Tambocor)

  • flecainide (Tambocor) is used in the treatment of supraventricular tachycardia.


  • Dosage: a history of MI.

  • PO: 100 mg every 12 hours, increased by 50 mg bid until arrhythmia is resolved (maximum daily dose of 400 mg).



Propafenone rythmol
propafenone (V-tach). (Rythmol)

  • propafenone(Rythmol) is used in the treatment of both ventricular tachycardia and supraventricular tachycardia


  • Dosage: (V-tach).

  • PO: 150 mg every 8 hours, may be increased up to 300 mg every 8 – 12 hours.




2 class ii antiarrhythmic drugs beta blockers
2. Class II antiarrhythmic drugs (beta blockers) altered taste, nausea, vomiting and constipation.

  • This class of drugs are the beta blockers which block the effects of catecholamines at the β receptors, thereby decreasing sympathetic activity and resulting in a decrease in the heart rate.



3 class iii antiarrhythmic drugs k 1 channel blockers
3. Class III antiarrhythmic drugs and atrial flutter. (K1+ channel blockers)

  • By blocking K1+ channels, these drugs lengthen the action potential (by lengthening the refractory period/resting stage).





Amiodarone cordarone pacerone
amiodarone class. (Cordarone, Pacerone)

  • amiodarone is indicated for the treatment of life threatening ventricular arrhythmias, but only when the patient is unresponsive to less toxic agents (i.e. dofetilide or ibutilide)


  • Dosage: class.

  • PO: 800 – 1600 mg/day in 1 – 2 doses for 1 – 3 weeks, then 600 – 800 mg/day in 1 – 2 doses for 1 month, then 400 mg/day for maintenance





  • thyroid dysfunction affecting almost every part of the body:

  • photosensitivity

  • involuntary movement

  • tremors

  • bradycardia


  • hypotension affecting almost every part of the body:

  • visual problems

  • discoloration of the skin

  • decreased libido


Dofetilide tikosyn
dofetilide affecting almost every part of the body: (Tikosyn)

  • dofetilide (Tikosyn) is indicated for the conversion of atrial fibrillation and atrial flutter to normal sinus rhythm


  • Dosage: affecting almost every part of the body:

  • PO: Initial dose is 500 μg bid; maintenance dose is 250 μg bid



Ibutilide corvert
ibutilide arrhythmias. It’s most common adverse effects are dizziness, headache and chest pain. (Corvert)

  • ibutilideis indicated for the conversion of atrial fibrillation and atrial flutter to normal sinus rhythm, especially within 1 week of bypass surgery.




4 class iv antiarrhythmic drugs
4. Class IV antiarrhythmic drugs arrhythmias. It’s most common adverse effects are headache and nausea.

  • These drugs prevent the movement of calcium into myocardial cells which slows depolarization and decreases the heart rate.





  • Verapamil arrhythmias including atrial flutter, atrial fibrillation and supraventricular tachycardia (Calan, Verelan, Isoptin)

  • Diltiazem (Cardizem, Dilacor, Tiazac)


  • Adverse effects include: arrhythmias including atrial flutter, atrial fibrillation and supraventricular tachycardia

  • headache

  • Dizziness

  • GI disturbances

  • orthostatic hypotension


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