Which drug is used in emergencies to treat ventricular fibrillation or tachycardia?

Amiodarone is a key drug used in emergencies, particularly for treating ventricular fibrillation and ventricular tachycardia. This medication is classified as an antiarrhythmic agent and is effective due to its ability to prolong the action potential and refractory period in cardiac tissues. This action stabilizes the cardiac rhythm and helps restore normal heart function during critical conditions such as cardiac arrest.

In emergency situations, when a patient presents with ventricular fibrillation, rapid intervention is crucial, and amiodarone serves as a first-line treatment. The drug can be administered through various routes, including intravenous injection, making it suitable for use in acute care settings.

While other medications listed serve important roles in cardiac and other emergency interventions, they do not have the same specific application in the management of ventricular fibrillation or tachycardia as amiodarone does.