ethical drug vs prescription medicine

ethical drug and prescription medicine both are nouns.

Word	Noun	Adjective	Verb	Adverb
ethical drug	Yes	No	No	No
prescription medicine	Yes	No	No	No

As nouns, ethical drug and prescription medicine are synonyms defined as:

ethical drug and prescription medicine: a drug that is available only with written instructions from a doctor or dentist to a pharmacist

Other synonyms of ethical drug include prescription, prescription drug.

ethical drug (noun)	prescription medicine (noun)
a drug that is available only with written instructions from a doctor or dentist to a pharmacist	a drug that is available only with written instructions from a doctor or dentist to a pharmacist