Ethical drug and Patent medicine

Ethical drug noun - A drug that is available only with written instructions from a doctor or dentist to a pharmacist.

Patent medicine and ethical drug are semantically related In some cases you can use "Patent medicine" instead a noun phrase "Ethical drug".

Patent medicine noun - Medicine that is protected by a patent and available without a doctor's prescription.

Ethical drug and patent medicine are semantically related in proprietary medicine topic. You can use "Ethical drug" instead a noun phrase "Patent medicine".