antiarrhythmic vs medicament

antiarrhythmic and medicament both are nouns.

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

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

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

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

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