What is an orphan drug?
An orphan drug is a drug for a rare disease or condition. Some rare disease treatments have been “orphaned” or discontinued because there was not enough financial incentive to continue development or production. The Orphan Drug Act incentivizes drug development for rare diseases.
Orphan Drug Definition An orphan drug is defined in the 1984 amendments of the U.S. Orphan Drug Act (ODA) as a drug intended to treat a condition affecting fewer than 200,000 persons in the United States, or which will not be profitable within 7 years following approval by the FDA.

我国对“新药”的定义包含了化学药1类( 境内外均未上市的创新药) 及5. 1 类( 境外上市的原研药品) 、生物制品1 类( 未在国内外上市的生物制品) 及2 类( 单克隆抗体) 、中药和疫苗; 美国食品药品监督管理局( U. S． Food and Drug Administration，FDA) 将“新型药物( Novel Drug) ”定义为“药品中含有的新分子实体( New Molecular Entities，NMEs) 的药物和新治疗性生物产品”，不包含疫苗、致敏产品、血液和血液制品、血浆衍生物、细胞和基因治疗产品; 日本医疗器械审评审批机构( Pharmaceuticals and Medical Devices Agency，PMDA) 在《上市药品清单》( List of Approved Products) 中对上市新药评审类别也进行了详细的类别划分，将“新药”定义为具有新有效成分或化学结构，以及因剂型、规格、给药途径的变化导致药理作用发生改变的药物，主要包括具有新的活性成分、具有新的适应证、具有新的剂型、具有新的给药途径等。