Final answer:
Dopamine D2 receptor blockers used as antiemetics include chlorpromazine from the phenothiazines class and ondansetron, which is marketed as Zofran.
Step-by-step explanation:
Dopamine D2 receptor blockers are used as antiemetics, and they are often discussed in medical classes when covering treatments for symptoms such as nausea and vomiting. Phenothiazines are a class of drugs that include antiemetic agents such as chlorpromazine, which can also potentiate analgesics, sedatives, and general anesthetics. Additionally, ondansetron, a medication under the brand name Zofran, is commonly used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, or surgery.