antidiuretic vs medicinal drug

antidiuretic and medicinal drug both are nouns.

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

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

antidiuretic: a drug that limits the formation of urine
medicinal drug: (medicine) something that treats or prevents or alleviates the symptoms of disease

Other hypernyms of antidiuretic include medicament, medication, medicine.

antidiuretic (noun)	medicinal drug (noun)
a drug that limits the formation of urine	(medicine) something that treats or prevents or alleviates the symptoms of disease