Cardio: Class III Antiarrhythmics Flashcards

1
Q

The potassium current is found in which phases of the cardiac action potential?

A

2 (during which it competes with calcium) and 3 (during which it repolarizes the cell)

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2
Q

What is the mechanism of class III antiarrhythmics?

A

They block potassium channels, thus prolonging both depolarization and repolarization of the His-Purkinje fibers and cardiac myocytes. (Think of the mariachi singer throwing aside the banana curtain, thus flattening out the action-potential wave.)

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3
Q

The class III antiarrhythmics uniquely share ______________.

A

some properties of all the categories of drugs: they block inactivated sodium channels (I), block beta-receptors (II), and block calcium channels (IV) (Think of the three singers counting off “uno dos tres cuatro!”)

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4
Q

What suffix is common in the class III drugs?

A

-tilide (as in dofetilide and ibutilide)(Think of the “TILl I DiE” marriage proposal to the girl sitting at the table.)

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5
Q

Which class III drug has a lot of beta-blocking ability?

A

Sotalol (Think of the guy knocking over soda bottles with his beta-bugle.)

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6
Q

Which arrhythmias are treatable with class III drugs?

A

Both supraventricular (atrial) and ventricular arrhythmias, such as atrial fibrillation (they specifically control the rhythm of atrial fibrillation)

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7
Q

What neurologic side effects does amiodarone have?

A

Tremor, ataxia, neuropathy, and sleep disturbances

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8
Q

What is symbolized by the singers’ glasses?

A

The fact that amiodarone can cause gray corneal deposits (in almost all patients with a couple weeks)

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9
Q

True or false: amiodarone causes hyperthyroidism.

A

True, but it can also cause hypothyroidism! (Think of the two singers: one has an untied bowtie, and the other has a large, tied bowtie.)

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10
Q

What cardiopulmonary side effects does amiodarone have?

A

Pulmonary fibrosis (duh); heart block (represented by the singer’s heart-block-shaped hat); and torsades (like every potassium-channel-blocking agent) –though dofetilide, ibutilide, and sotalol are more likely to cause torsades(Think of the twisting banners everywhere.)

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11
Q

Dermatologically, amiodarone can _______________.

A

cause gray-blue discoloration in sun-exposed areas

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12
Q

What hepatic effects does amiodarone have?

A

It can cause hypersensitivity hepatitis, and it is an inhibitor of CYP450.

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