Class III: Potassium channel blockers

Definition

Class III: Potassium channel blockers are a group of antiarrhythmic drugs that work by prolonging the repolarization phase of the cardiac action potential. This helps to stabilize abnormal heart rhythms and is used in the treatment of various types of dysrhythmias.

5 Must Know Facts For Your Next Test

1. Class III drugs primarily block potassium channels, leading to prolonged repolarization and an increased refractory period.
2. Common examples include amiodarone, sotalol, and dofetilide.
3. These drugs can be used to treat both atrial and ventricular dysrhythmias.
4. Amiodarone has multiple effects including blocking sodium and calcium channels as well as beta-adrenergic receptors.
5. Side effects may include pulmonary toxicity, thyroid dysfunction, and proarrhythmia (new or worsened arrhythmias).

Review Questions

• What is the primary mechanism of action for Class III potassium channel blockers?
• Name three common Class III potassium channel blocker drugs.
• What are some potential side effects of amiodarone?

Related terms

Dysrhythmia:

An abnormal heart rhythm.

Repolarization:

The phase during which the cardiac muscle cells return to their resting state after depolarization.

Antiarrhythmic Drugs:

Medications used to treat irregular heart rhythms.