Which medication treats irregular heartbeats (arrhythmias) and can also relieve pain and numb the skin?

• A. Digoxin
• B. Lidocaine (Xylocaine)
• C. Amiodarone
• D. Procainamide

Answer: (B)

Lidocaine is useful here because it has two distinct roles: it treats certain irregular heartbeats and also acts as a local anesthetic. As an antiarrhythmic, lidocaine blocks fast sodium channels in cardiac cells, especially in depolarized or ischemic tissue, which shortens the action potential and reduces abnormal automaticity and conduction. This makes it effective for ventricular arrhythmias. As a local anesthetic, lidocaine also blocks sodium channels in peripheral nerves, preventing nerve impulses and producing numbness and pain relief where it’s applied. That combination of stabilizing heart rhythms and numbing tissue is why lidocaine fits both parts of the question. The other drugs listed are mainly antiarrhythmics and do not have the local anesthetic effects needed for numbness and pain relief.