Cardiovascular Drugs and Medications Q 80

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Johanna has ventricular ectopy, which of the following drugs is the first line used to treat her condition?

  

     A. quinidine (Cardioquin)

     B. digoxin (Lanoxin)

     C. procainamide ( Pronestyl)

     D. lidocaine (Xylocaine)

    

    

Correct Answer: D. lidocaine (Xylocaine)

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Lidocaine is the only choice used to treat ventricular ectopy. Quinidine and digoxin are class IA antiarrhythmics.

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Option A: Quinine is a derivative of the bark of the South American cinchona tree. Quinidine is a stereoisomer of quinine; it is a “class 1a antiarrhythmic drug” and also an antimalarial agent. Class 1a antiarrhythmic agents (for example – quinidine, procainamide, disopyramide, ajmaline) work by inhibiting the fast inward sodium current, depressing the phase 0 of the action potential hence dampening the excitability of cardiac muscles which in turn prolongs the action potential and decreases automaticity.

Option B: Digoxin comes from the foxgloves plant known as Digitalis purpurea. It is a cardiotonic glycoside and belongs to the digitalis class. It increases the force of contraction of the heart by reversibly inhibiting the activity of the myocardial Na-K ATPase pump, an enzyme that controls the movement of ions into the heart. Digoxin has vagomimetic effects on the AV node.

Option C: Procainamide is a medication used in the management and treatment of ventricular arrhythmias, supraventricular arrhythmias, atrial flutter, atrial fibrillation, AV nodal reentrant tachycardia, and Wolf-Parkinson-White syndrome. It is a Class 1A antiarrhythmic agent. Procainamide is a class 1A antiarrhythmic that binds to fast sodium channels inhibiting recovery after repolarization. It also prolongs the action potential and reduces the speed of impulse conduction. This action results in decreased myocardial excitability, slowed conduction velocity, and reduced myocardial contractility.

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