The overall purpose of the joint FDA/USP (Food and Drug Administration/United States Pharmacopeia) Substance Registration System (SRS) is to support health information technology initiatives by generating UNIIs for substances in drugs, biologics, foods, and devices. The UNII (Unique Ingredient Identifier) is a non- proprietary, free, unique, unambiguous, non semantic, alphanumeric identifier based on a substance’s molecular structure and/or descriptive information. The procedures and management of the SRS are provided by the SRS Board. The SRS Board includes experts from both FDA and USP. The SRS operating procedures defined by the SRS Board are detailed in the SRS Manual.
The UNII is a core component of the US Federal Medication Terminology, it is used for product labeling, to assist in the generation of RxNorm, as an identifier for drug ingredients and allergens and in the future will be a component of the Environmental Protection Agency’s Substance Registry System. The UII is useful for understanding data contained in NLM’s (National Library of Medicine) Unified Medical Language System, National Cancer Institutes Enterprise Vocabulary Service, FDA Data Standards Council website, VA National Drug File Reference Terminology, FDA Inactive Ingredient Query Application and, proximately, USP Dictionary of USAN and International Drug Names.