What is the term for a drug that is used to treat a disease affecting fewer than 200,000 patients?

The term for a drug that is used to treat a disease affecting fewer than 200,000 patients is known as an "Orphan Drug." Orphan drugs are developed specifically to treat rare diseases and conditions that may not be financially viable for pharmaceutical companies to pursue under normal market conditions due to the small patient population. Because of this, regulatory incentives are often provided to encourage the development of orphan drugs, including tax credits and exclusive market rights.

This designation is important as it fosters innovation and ensures that patients with rare conditions have access to necessary treatments that might otherwise be overlooked. In contrast, terms like "Brand Name" refer to the proprietary name given to a drug by the manufacturer while "Generic Drug" denotes a medication that is equivalent to a brand-name product in dosage, strength, and administration but is sold under its chemical name. An "Abbreviated New Drug Application" is a request for approval to market a generic drug and does not specifically refer to drugs for rare diseases.