Which of the following is an antiarrhythmic medication?

Amiodarone is an antiarrhythmic medication, widely used in the management of various types of cardiac arrhythmias. It works by modifying the electrical signals in the heart, helping restore a normal rhythm. Amiodarone is particularly effective for treating ventricular and atrial arrhythmias and is often used in emergency settings due to its properties that prolong the action potential and refractory period in myocardial tissue.

The other medications listed serve different purposes. Dopamine is primarily a vasopressor and inotrope used to treat shock and heart failure; aspirin is an antiplatelet agent often used to prevent blood clots; and metoprolol, while a beta-blocker that can also have effects on heart rhythm, is mainly used for hypertension and heart failure management rather than specifically classified as an antiarrhythmic agent. Understanding the specific uses and classifications of these medications is crucial in clinical practice.