Cardio: Class III Antiarrhythmics Flashcards
The potassium current is found in which phases of the cardiac action potential?
2 (during which it competes with calcium) and 3 (during which it repolarizes the cell)
What is the mechanism of class III antiarrhythmics?
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.)
The class III antiarrhythmics uniquely share ______________.
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!”)
What suffix is common in the class III drugs?
-tilide (as in dofetilide and ibutilide)(Think of the “TILl I DiE” marriage proposal to the girl sitting at the table.)
Which class III drug has a lot of beta-blocking ability?
Sotalol (Think of the guy knocking over soda bottles with his beta-bugle.)
Which arrhythmias are treatable with class III drugs?
Both supraventricular (atrial) and ventricular arrhythmias, such as atrial fibrillation (they specifically control the rhythm of atrial fibrillation)
What neurologic side effects does amiodarone have?
Tremor, ataxia, neuropathy, and sleep disturbances
What is symbolized by the singers’ glasses?
The fact that amiodarone can cause gray corneal deposits (in almost all patients with a couple weeks)
True or false: amiodarone causes hyperthyroidism.
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.)
What cardiopulmonary side effects does amiodarone have?
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.)
Dermatologically, amiodarone can _______________.
cause gray-blue discoloration in sun-exposed areas
What hepatic effects does amiodarone have?
It can cause hypersensitivity hepatitis, and it is an inhibitor of CYP450.