dosage vs medicinal drug

dosage and medicinal drug both are nouns.

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

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

dosage: a measured portion of medicine taken at any one time
medicinal drug: (medicine) something that treats or prevents or alleviates the symptoms of disease

Other hypernyms of dosage include medicament, medication, medicine.

dosage (noun)	medicinal drug (noun)
a measured portion of medicine taken at any one time	(medicine) something that treats or prevents or alleviates the symptoms of disease
the quantity of an active agent (substance or radiation) taken in or absorbed at any one time