In December 2021, the FDA Substance Registration System (FDA SRS) will move from NLM to FDA. A redirect will be put in place from this URL. Please see the NLM Technical Bulletin article for more information.
NOTE: UNIIs are generated based on scientific identity characteristics using ISO 11238 data elements. UNII availability does not imply any regulatory review or approval. Synonyms and mappings are based on the best public information available at the time of publication. Please report any problems/errors associated with this data to FDA-SRS@fda.hhs.gov.