dosage vs medicament

dosage and medicament both are nouns.

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

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

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

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

dosage (noun)	medicament (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