Review Question - QID 213243

A 58-year-old man presents to his primary care physician with a 3-week history of increasing pain in his legs and feet. Specifically, he says that he has been getting electric shock sensations that started in his feet, but have progressed up his leg. In addition, the pain is accompanied by numbness and tingling in his hands and feet bilaterally. His past medical history is significant for poorly controlled type 2 diabetes mellitus. Given these symptoms, his physician prescribes a new drug to help him cope with these symptoms. Which of the following is the mechanism of action for the medication that was most likely prescribed in this case?