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Pharm II Unit II > Antiarrhythmics > Flashcards

Antiarrhythmics Flashcards

1
Q

What is the obvious downside of antiarrhythmic agents?

A

They can precipitate lethal arrhythmias

But you still have to treat b/c they can be life threatening

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2
Q

Cardiac arrhythmias have two basic causes:

A

Disturbances in impulse formation

Disturbances in impulse conduction

(Or both)

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3
Q

Precipitating factors for cardiac arrhythmias

A

Ischemia/hypoxia

Alkalosis, electrolyte abnormalities

Excessive catecholamine exposure

Drug toxicities

Overstretching cardiac fibers

Scarred/diseased tissue

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4
Q

What is the most common mechanism for arrhythmias?

A

Unidirectional block

The impulse traveling through the block is extinguished in the anterograde direction

THe conduction pathway now can re-enter in the retrograde direction —> reentry arrhythmia circuit

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5
Q

What is the aim of therapy for arrhythmias?

A

Reduce ectopic pacemaker activity

Modify conduction or refractories to disable reentry

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6
Q

Main mechanisms for antiarrhythmics

A

Sodium channel blockade (Class I)
Blockade of sympathetic effects (Class II)
Prolongation of the effective refractory period (Class III)
Calcium channel blockade (Class IV)

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7
Q

Class IA antiarrhythmics MOA

A

Preferentially block OPEN or ACTIVATED Na+ channels

Lengthens the DURATION of action potentials

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8
Q

Class IA antiarrhythmics

A

Quinidine

Procainamide

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9
Q

Class IB antiarrhythmics MOA

A

Block INACTIVATED sodium channels —> shorten the duration of action potentials

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10
Q

Class IB antiarrhythmics

A

Lidocaine

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11
Q

Class IC antiarrhythmics MOA

A

Bind to ALL sodium channels - no effect on the duration of action potentials

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12
Q

Class IC antiarrhythmics

A

Flecainide

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13
Q

Class II antiarrhythmics MOA

A

Reduce adrenergic activity on the heart

BETA BLOCKERS

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14
Q

Class III antiarrhythmics MOA

A

K+ channel inhibitors —> prolong the effective refractory period

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15
Q

Class III antiarrhythmics

A

Amiodarone

Sotalol

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16
Q

Class IV antiarrhythmics MOA

A

Calcium channel blockers —> decrease HR, contractility

Verapamil, diltiazem

17
Q

What is the secondary action of Quinidine?

A

Blocking K+ channels (prolongs the action potential duration and effective refractory period)

18
Q

Which antiarrhythmic is the “Jack of all trades”?

A

Quinidine

It was the first (that’s why it’s Class IA)

Has “Atropine-like effect”

Rarely used these days b/c we have newer drugs with fewer side effects

19
Q

What drug is used for acute or chronic treatment of supraventricular and ventricular arrhythmias?

A

Quinidine

20
Q

What is the major adverse effect of Quinidine?

A

Torsade de pointes (treat with Mg)

21
Q

Patients with _______ are at great risk of quinidine syncope/Torsade

A

Long QT

22
Q

What makes Procainamide unique from the other Class IA drug (Quinidine)?

A

IT’S a MOTHERFUCKING HIP DRUG —> SLE IN SLOW ACETYLATORS

23
Q

Lidocaine blocks ________

A

Inactivated Na+ channels —> preferentially affects damaged tissue

24
Q

DOC for acute ventricular arrhythmias

A

Lidocaine - administered IV, rapid onset

25
Q

Adverse effects of Lidocaine

A

Least toxic, least negative inotropic

CONVULSIONS

26
Q

Flecainide (Tambocor) strongly blocks _______.

A

All Na+ channels —> strong pro-arrhythmic effect

That’s why it’s a last-ditch effort drug for supraventricular arrhythmias and life-threatening ventricular arrhythmias

27
Q

Which specific beta blockers are Class II antiarrhythmics?

A

Propranolol (Inderal) - non-specific
Acebutolol (Sectral) - B1 specific
Esmolol (Breviblock) - B1 but IV only

28
Q

Which class of antiarrhythmic is Amiodarone?

A

Class III - blocks K+ channels but also has some Class I, II, and IV properties

29
Q

DOC for ventricular arrhythmias, used by ACLS

A

Amiodarone

30
Q

Effective against both supraventricular and ventricular arrhythmias

A

Amiodarone

31
Q

What are the things that make Amiodarone special?

A

NO TORSADE DE POINTES

Can cause pulmonary fibrosis if used long term

Gets deposited in tissues —> yellow cornea, grayishblue skin

Thyroid dysfunction (iodine derivative)

32
Q

Non-selective BB used as a Class III antiarrhythmic

A

Sotalol (Betapace)

Used in ventricular and supraventricular arrhythmias like amiodarone but unlike it, this one will cause TORSADE

33
Q

What are the indications for Class IV antiarrhythmics?

A

(Verapamil and Diltiazem)

Reentrant supraventricular tachycardia

PSVT (for long term prophylaxis)

A fib and flutter

**CCBs are only effective in the atria

34
Q

DOC for acute PSVT and WPW SYndrome

A

Adenosine

Enhanced K+ conductance and inhibition of cAMP-induced Ca influx (basically resets the heart)

Effective only for reentry arrhythmias

35
Q

PSVT treatment order

A

ACUTE:
Adenosine
Esmolol
CCBs (IV)

CHRONIC:
Beta blockers
CCBs

36
Q

DOC for Torsade de pointes

A

Magnesium (mechanism unknown)

Can also be used to treat seizures associated with toxemia in pregnancy

37
Q

Both hyperkalemia and hypokalemia are ________

A

Arrhythmogenic

Pharm II Unit II (8 decks)

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