Class III antidysrhythmic medications

Class III antidysrhythmic medications

Also known as potassium channel blockers, these are used to treat life-threatening dysrhythmias like ventricular tachycardia or ventricular fibrillation.

Potassium channel blockers

Medications that block potassium channels, prolonging repolarization and the refractory period of the heart.

Amiodarone and Dronedarone

Examples of potassium channel blockers that block potassium, sodium, calcium channels, and beta-adrenergic receptors.

QT interval

The length of time from the beginning of the QRS complex to the end of the T wave on an ECG, indicating ventricular depolarization and repolarization.

Torsades de pointes

A potentially life-threatening dysrhythmia that can degenerate into ventricular fibrillation, associated with prolonged QT interval.

Black Box warning

A warning indicating that a drug has serious or life-threatening risks; for example, amiodarone's use is restricted to life-threatening dysrhythmias.

Pro-dysrhythmic properties

The tendency of antidysrhythmic medications to potentially worsen existing dysrhythmias or cause new ones.

Contraindications for Class III medications

Include second- or third-degree heart block, sick sinus syndrome, severe bradycardia, and certain toxicities from previous medications.

CYP3A4 substrates

Amiodarone and dronedarone are significant substrates of this enzyme, affecting their levels based on interactions with inducers or inhibitors.

Nursing considerations for Class III antidysrhythmics

Include baseline assessments, monitoring for side effects, evaluating effectiveness of therapy, and patient self-administration teaching.

Safe self-administration

Patients must take their medications exactly as prescribed without abrupt discontinuation to prevent reemergence of dysrhythmias.

Organ toxicities

Potential side effects of potassium channel blockers, particularly pulmonary and hepatotoxicity with prolonged use.

Photosensitivity

One of the serious complications of amiodarone that can cause skin to turn a bluish-gray color with sun exposure.