How Well Do You Know About Antiarrhythmic Drugs?

1.

Which class of antiarrhythmic drugs block Na+ channels?

A.

Class I
B.

Class II
C.

Class III
D.

Class IV

Correct Answer
A. Class I

Explanation
Class I antiarrhythmic drugs block Na+ channels.

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2.

Which class of antiarrhythmic drugs are Beta Adrenergic Receptor Blockers?

A.

Class I
B.

Class II
C.

Class III
D.

Class IV

Correct Answer
B. Class II

Explanation
Beta Adrenergic Receptor Blockers are a class of antiarrhythmic drugs that work by blocking the beta adrenergic receptors in the heart, thus reducing the effects of adrenaline and sympathetic stimulation. This class of drugs is commonly used to treat conditions such as hypertension, angina, and certain arrhythmias. Class II antiarrhythmic drugs, which include beta blockers like propranolol and metoprolol, specifically target the beta adrenergic receptors and are therefore the correct answer in this case.

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3.

Which class of antiarrhythmic drugs block K+ channels?

A.

Class I
B.

Class II
C.

Class III
D.

Class IV

Correct Answer
C. Class III

Explanation
Class III antiarrhythmic drugs block K+ channels. These drugs prolong the action potential duration by inhibiting the outward K+ current during repolarization. This results in a lengthening of the refractory period and helps to prevent re-entry arrhythmias. Examples of class III antiarrhythmic drugs include amiodarone, sotalol, and dofetilide.

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4.

Which class of antiarrhythmic drugs block Ca++ channels?

A.

Class I
B.

Class II
C.

Class III
D.

Class IV

Correct Answer
D. Class IV

Explanation
Class IV antiarrhythmic drugs block Ca++ channels.

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5.

Which drugs are Class I Subtype A antiarrhythmic drugs?

A.

Quinidine
B.

Lidocaine
C.

Procainamide

Correct Answer(s)
A. Quinidine
C. Procainamide

Explanation
Quinidine and Procainamide are Class I Subtype A antiarrhythmic drugs. These drugs work by blocking sodium channels in the heart, which helps to stabilize the heart's electrical activity and prevent abnormal heart rhythms. Lidocaine, on the other hand, is a Class Ib antiarrhythmic drug, which works by blocking sodium channels in a different manner. Therefore, the correct answer is Quinidine and Procainamide.

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6.

Which subclass of Class I antiarrhythmic drugs reduces automaticity, delays conduction, and increases refractory period?

A.

A
B.

B
C.

C

Correct Answer
A. A

Explanation
Class I antiarrhythmic drugs are classified into three subclasses: A, B, and C. Subclass A drugs, such as quinidine and procainamide, reduce automaticity (the ability of cardiac cells to generate electrical impulses), delay conduction (the spread of electrical impulses through the heart), and increase the refractory period (the time during which the heart cannot be re-stimulated). Therefore, the correct answer is A.

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7.

Which subclass of Class I antiarrhythmic drugs reduces ectopic automaticity?

A.

A
B.

B
C.

C

Correct Answer
B. B

Explanation
Class I antiarrhythmic drugs are classified based on their effects on cardiac sodium channels. Subclass B, also known as beta blockers, reduce ectopic automaticity by blocking the effects of catecholamines on the heart. This reduces the sympathetic stimulation and decreases the automaticity of the ectopic pacemaker cells, helping to prevent abnormal heart rhythms.

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8.

Which subclass of Class I antiarrhythmic drugs reduces automacity and delays conduction?

A.

A
B.

B
C.

C

Correct Answer
C. C

Explanation
Class I antiarrhythmic drugs are classified into three subclasses: Class IA, Class IB, and Class IC. Class IC drugs, such as flecainide and propafenone, are known to reduce automacity (the ability of cardiac cells to initiate electrical impulses) and delay conduction (the spread of electrical impulses through the heart). Therefore, the correct answer is C.

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9.

Which of the following drugs are Class I subtype B antiarrhythmic drugs?

A.

Lidocaine
B.

Mexilitine
C.

Quinidine
D.

Tocainide

Correct Answer(s)
A. Lidocaine
B. Mexilitine
D. Tocainide

Explanation
Lidocaine, Mexilitine, and Tocainide are classified as Class I subtype B antiarrhythmic drugs. These drugs work by blocking sodium channels in the heart, which helps to stabilize the heart's electrical activity and prevent abnormal heart rhythms. Class I antiarrhythmic drugs are further divided into subclasses based on their specific effects on the sodium channels. Subtype B drugs, including Lidocaine, Mexilitine, and Tocainide, primarily affect the recovery phase of the action potential and are used to treat ventricular arrhythmias. Quinidine, on the other hand, is a Class I subtype A antiarrhythmic drug, which affects the initial phase of the action potential and is used for treating atrial arrhythmias.

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10.

Which of the following drugs are Class I subtype C antiarrhythmic drugs?

A.

Procainamide
B.

Flecainide
C.

Propafenone

Correct Answer(s)
B. Flecainide
C. Propafenone

Explanation
Flecainide and Propafenone are both Class I subtype C antiarrhythmic drugs. Class I antiarrhythmic drugs are classified based on their effect on sodium channels in cardiac cells. Subtype C specifically refers to drugs that have both sodium channel blocking and potassium channel blocking effects. Procainamide, on the other hand, is a Class I subtype A antiarrhythmic drug, which means it primarily blocks sodium channels. Therefore, the correct answer is Flecainide and Propafenone.

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11.

What are the two Beta Adreneric Receptor Blocker drugs from Class II antiarrhythmic drugs?

Correct Answer(s)
Propranolol, Esmolol

Explanation
Propranolol and Esmolol are both Beta Adreneric Receptor Blocker drugs from Class II antiarrhythmic drugs. These drugs work by blocking the beta adrenergic receptors in the heart, which reduces the effects of adrenaline and slows down the heart rate. Propranolol is a nonselective beta blocker, meaning it blocks both beta-1 and beta-2 receptors, while Esmolol is a selective beta-1 blocker. Both drugs are commonly used to treat various heart conditions, including arrhythmias.

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12.

Which of the following are Class III K+ channel blockers that delay repolarization and increase refractory period?

A.

Amiodarone
B.

Esmolol
C.

Ibutilide
D.

Sotalol

Correct Answer(s)
A. Amiodarone
C. Ibutilide
D. Sotalol

Explanation
Amiodarone, Ibutilide, and Sotalol are Class III K+ channel blockers that delay repolarization and increase the refractory period. These medications work by blocking the potassium channels in cardiac cells, which prolongs the action potential duration and delays repolarization. This leads to a lengthened refractory period, reducing the risk of arrhythmias. Amiodarone is a broad-spectrum antiarrhythmic drug, while Ibutilide and Sotalol are specifically used for the treatment of atrial fibrillation and ventricular arrhythmias.

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13.

What are the Class IV Calcium Channel Blocker Drugs?

Correct Answer(s)
Verapamil, Diltiazem

Explanation
Verapamil and Diltiazem are classified as Class IV Calcium Channel Blocker Drugs. These medications work by blocking the movement of calcium ions into the smooth muscle cells of the heart and blood vessels, leading to relaxation of the muscles and dilation of the blood vessels. This results in decreased heart rate, reduced blood pressure, and improved blood flow. Verapamil and Diltiazem are commonly used to treat conditions such as high blood pressure, angina, and certain heart rhythm disorders.

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