Amiodarone

Amiodarone is an antiarrhythmic medication used to treat and prevent serious abnormal heart rhythms. It affects cardiac electrical activity and has effects across several ion-channel and receptor systems.

Cardiac action potential: The changing membrane voltage that drives electrical activation and recovery in heart muscle cells. Amiodarone alters the electrical signals that shape this cycle.
Ventricular tachycardia: A rapid heart rhythm originating in the ventricles, which can impair circulation or become life-threatening. Amiodarone is used to treat selected sustained or recurrent forms.
Pulmonary toxicity: Lung injury caused by a drug or other exposure, sometimes involving inflammation or scarring. Amiodarone can cause serious lung injury, including pneumonitis and fibrosis.
Dronedarone: An antiarrhythmic related to amiodarone but modified to reduce iodine-related effects and tissue accumulation. It avoids some amiodarone toxicities but is unsuitable for certain patients and arrhythmias.
Potassium channel: A membrane protein that selectively conducts potassium ions across a cell membrane. Blocking cardiac potassium currents prolongs electrical recovery and the refractory period.
Atrial fibrillation: An irregular rhythm caused by disorganized electrical activity in the atria. Amiodarone can help maintain sinus rhythm in selected patients.
Thyroid dysfunction: Impaired thyroid hormone production or regulation, resulting in underactivity or overactivity. Amiodarone's high iodine content and thyroid effects can cause either hypothyroidism or thyrotoxicosis.
Sotalol: A beta blocker with potassium-channel-blocking activity used to treat selected arrhythmias. Its more focused actions contrast with amiodarone's broad pharmacology and different toxicity profile.
Sodium channel: A membrane protein that conducts sodium ions and helps generate rapid electrical signals in excitable cells. Amiodarone's sodium-channel effects slow conduction through cardiac tissue.
Ventricular fibrillation: A chaotic ventricular rhythm that prevents effective pumping and causes cardiac arrest. Intravenous amiodarone may be used for refractory ventricular fibrillation during resuscitation.

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