antiarrhythmic vs antiarrhythmic drug

antiarrhythmic and antiarrhythmic drug both are nouns.

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

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

antiarrhythmic and antiarrhythmic drug: a drug used to treat an abnormal heart rhythm

Other synonyms of antiarrhythmic include antiarrhythmic medication.

antiarrhythmic (noun)	antiarrhythmic drug (noun)
a drug used to treat an abnormal heart rhythm	a drug used to treat an abnormal heart rhythm