Review Question - QID 5536

A 55-year-old male undergoes surgery on his right shoulder. In the preoperative holding area, he reveals that his older brother and mother have had serious problems with general anesthesia in the past. Twenty minutes into the surgery, the surgeon notices skin mottling and increasing limb stiffness, making it hard to manipulate the arm. He calls for muscle relaxation, but is told a depolarizing neuromuscular blocker has already been given. End-tidal CO2 rises significantly, his pulse rate is now 120-130 bpm, and his urine appears dark. In response the anesthesiologist disconnects the vaporizer, begins hyperventilation with oxygen, and stops all triggering agents. In addition to the steps above, which of the following medications should be administered as an antidote?