Which of the following is classified as a Class 1B antiarrhythmic agent?

Lidocaine is identified as a Class 1B antiarrhythmic agent primarily due to its mechanism of action and its specific pharmacological properties. Class 1B agents primarily function by blocking sodium channels, particularly during the depolarization phase of the cardiac action potential. This helps to stabilize the cardiac membrane, thereby reducing excitability and preventing certain types of arrhythmias.

Lidocaine is particularly effective in treating ventricular arrhythmias, as it preferentially binds to sodium channels in the ischemic (damaged) tissues of the heart. It is commonly used in acute settings, such as post-myocardial infarction, to manage ventricular tachycardia. Its rapid onset and short duration of action make it a suitable choice for emergency scenarios.

In contrast, other options listed do not fall under the Class 1B category. For instance, Flecainide is a Class 1C antiarrhythmic that has a more potent sodium channel blockade and is used for both atrial and ventricular arrhythmias. Amiodarone is classified as a Class III antiarrhythmic agent due to its ability to prolong the action potential duration. Beta blockers are not classified as antiarrhythmics in the same way