antiemetic vs antiemetic drug

antiemetic and antiemetic drug both are nouns.

Word	Noun	Adjective	Verb	Adverb
antiemetic	Yes	No	No	No
antiemetic drug	Yes	No	No	No

As nouns, antiemetic and antiemetic drug are synonyms defined as:

antiemetic and antiemetic drug: a drug that prevents or alleviates nausea and vomiting

antiemetic (noun)	antiemetic drug (noun)
a drug that prevents or alleviates nausea and vomiting	a drug that prevents or alleviates nausea and vomiting