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PHARM EXAM 4 AND FINAL > Antidysrhythmic drugs > Flashcards

Antidysrhythmic drugs Flashcards

1
Q

What is the mechanism of action for the Class 1 drugs?

A

Block voltage-sensitive Na channels and reduce depolarization rise

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2
Q

What is the mechanism of action for the Class 2 drugs?

A

Beta adrenoceptor antagonists

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3
Q

What is the mechanism of action for the Class 3 drugs?

A

Prolong the refractory period of the myocardium

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4
Q

What is the mechanism of action for the Class 4 drugs?

A

Calcium antagonists; impair impulse propagation in damaged areas of the myocardium

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5
Q

When do Class 1 drugs bind most strongly?

A

When the Na channels are open or in the refractory state

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6
Q

What happens to Class 1 drugs when the Na channels are closed?

A

It gradually dissociates, so the block resides

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7
Q

T/F Class 1b drugs associate and dissociate rapidly

A

TRUE; within the time of a normal heart beat

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8
Q

What is a class 1b drug/

A

Lidocaine

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9
Q

T/F Lidocaine (1B) selectively binds to refractory channels during depolarized ischemic muscle

A

TRUE

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10
Q

What is Lidocaine (1B) useful for?

A

Control of ventricular dysrhythmias from any reason

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11
Q

T/F Class 1C drugs associate/dissociate more quickly than 1B drugs

A

FALSE; they are slow which means they achieve a steady state block that does not vary with the stage of the cycle

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12
Q

What is an example of a 1C drug?

A

Flecainide

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13
Q

What is Flecanide used to treat?

A

Ventricular tachycardias

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14
Q

What are some examples of class 1A drugs?

A

Quinidine (Horses)

Procainamide (Dog)

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15
Q

What species is Quinidine used in? Whats it used for?

A

Horses
Reverse atrial fibrillation
Indications: supra-ventricular arrhythmias esp atrial fibrillation

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16
Q

Procainamide is preferred in what species to do what?

A

Dogs

Maintenance of ventricular arrhythmias or ventricular tachycardia

17
Q

When would you NOT use Procainamide?

A

If the patient had a conduction block

18
Q

What is the mechanism of action of the 1A drugs?

A

Block the Na channels, just like the 1B and 1C drugs

19
Q

What effects do Beta-1 receptos have on the heart?

A

Increase rate and excitability

20
Q

What mechanism of action do class 2 drugs have?

A

Beta-1 antagonists

Reduce excitability due to sympathetic overactivity and reduce AV conduction in atrial tachycardias

21
Q

What are examples of Class 2 drugs?

A

Propranolol

Atenolol

22
Q

T/F PRopranolol is the most common class 2 drug

A

TRUE

23
Q

What special considerations come with Propranolol?

A

Bronchial muscle spasm is a possible SE; raise to full level over 3 days

24
Q

What does Propranolol do?

A

HR decreased
Prevent reflex tachycardia
Lowers blood pressure and reduces ventricular hypertrophy in cardiomyopathy and hyperthyroidism

25
Q

What is Atenolol used for? How is it different than Propranolol?

A

Used for supraventricular arrhythmias and excessive cardiac hypertrophy

May be longer acting

26
Q

What is the special feature of Class 3 drugs? What do these do?

A

Prolongs the cardiac action potential and icnreases the refractory period

Produces pronounces ventricular and supra-ventricular anti-dysrhythmic effects

27
Q

What would you use Class 3 drugs to treat?

A

Tachycardia

28
Q

What is an example of a Class 3 drug? When would you not want to use this?

A

Amiodarone

Contra-indicated for used with bradycardia

29
Q

What is the mechanism of action for Class 4 drugs?

A

Block voltage sensitive Ca channels

Shorten the plateu phase of the AP and reduce force of contraction

Inhibition of Ca suppresses ectopic beats

30
Q

What are some examples of the Class 4 drugs?

A

Verapamil and Diltiazem

31
Q

What Class 4 drug is preferred for IV administration? Long-term oral administration?

A

Verapamil for IV

Diltiazem: Long-term oral

32
Q

What would you use Class 4 drugs to treat?

A

Atrial tachycardias

33
Q

How do type 1A drugs differ from Class 1B and 1C drugs?

A

1A: can be used to treat atrial AND ventricular tachycardias

1b & 1C: Can only be used for ventricular tachycardias

All three work by blocking Na channels

34
Q

What could you use to treat an atrial tachycardia?

A

Qunidine (1A) Horses
Propranolol and Atenolol (2)
Verapamil and Diltiazem (4)

35
Q

What could you use to treat ventricular tachycardias/

A

Lidocaine (1B)
Flecainaide (1C; vet use probably unlikely)
Amiodarone (3)
Procainamide (1A) Dogs

PHARM EXAM 4 AND FINAL (13 decks)

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