antiepileptic vs medicinal drug

antiepileptic and medicinal drug both are nouns.

Word	Noun	Adjective	Verb	Adverb
antiepileptic	Yes	No	No	No
medicinal drug	Yes	No	No	No

As nouns, medicinal drug is a hypernym of antiepileptic; that is, medicinal drug is a word with a broader meaning than antiepileptic:

antiepileptic: a drug used to treat or prevent convulsions (as in epilepsy)
medicinal drug: (medicine) something that treats or prevents or alleviates the symptoms of disease

Other hypernyms of antiepileptic include medicament, medication, medicine.

antiepileptic (noun)	medicinal drug (noun)
a drug used to treat or prevent convulsions (as in epilepsy)	(medicine) something that treats or prevents or alleviates the symptoms of disease