antiarrhythmic vs medication

antiarrhythmic and medication both are nouns.

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

As nouns, medication is a hypernym of antiarrhythmic; that is, medication is a word with a broader meaning than antiarrhythmic:

antiarrhythmic: a drug used to treat an abnormal heart rhythm
medication: (medicine) something that treats or prevents or alleviates the symptoms of disease

Other hypernyms of antiarrhythmic include medicament, medicinal drug, medicine.

antiarrhythmic (noun)	medication (noun)
a drug used to treat an abnormal heart rhythm	the act of treating with medicines or remedies
	(medicine) something that treats or prevents or alleviates the symptoms of disease