noun
original drug; originator drug; brand-name drug
Pharmaceutical term for a drug that was first developed and marketed, as opposed to a generic copy. Used in medical, regulatory, and business contexts.
先発医薬品の特許が切れると、後発医薬品が発売される。
When the patent on the original drug expires, generic drugs are released.
Compound of 先発 (せんぱつ, 'first launch') + 医薬品 (いやくひん, 'pharmaceutical product'). The term is a modern coinage used in the pharmaceutical industry.