Digoxin (and its closely related cousin Digitoxin) is a cardiac glycoside which is used to treat various heart conditions including: atrial fibrillation, atrial flutter, and heart failure. It works by slowing down the rate at which the heart beats and increasing the contraction power of each beat. Digoxin and Digitoxin are also potent cardiac toxins when used in high dosages: they cause a person to undergo a fatal cardiac arrhythmia (irregular heartbeat). Both substances exist naturally, and they are found in the plant Digitalis lanata, commonly known as the woolly or Grecian foxglove.
Lenny Venito (Dominic 'Dom' Fabrigazzi, Jr.) previously played the role of Jake Nathan in Episode 1.1 (One (2001)).