Final answer:
Zofran, also known as ondansetron, is the commonly used antiemetic for preventing nausea and vomiting preoperatively.
Step-by-step explanation:
The commonly used antiemetic used preoperatively is Zofran. Zofran, also known as ondansetron, is a medication used to prevent nausea and vomiting associated with cancer chemotherapy, radiation therapy, or surgery. This antiemetic works by blocking the actions of chemicals in the body that can trigger nausea and vomiting. While other options like Versed, Pepcid, and Reglan are used in various medical scenarios, Zofran is specifically recognized for its efficacy in preventing postoperative nausea and vomiting (PONV) and is frequently used for this purpose in the preoperative setting.