Data sources
EntropyAPI serves US drug-reference data from public FDA and NLM sources. This page lists each source and what we use it for. The publishers’ notices are at the end.
| Source | Publisher | What we use it for | Updated |
|---|---|---|---|
| DailyMed (opens the publisher’s site) | National Library of Medicine (NLM) | Prescribing labels (SPL), label set IDs, products, packages and NDCs, FDA pharmacologic classes and billing units. | Daily |
| RxNorm (opens the publisher’s site) | NLM | Drug identifiers (RxCUIs), names and RxCUI history. | Monthly |
| Orange Book (opens the publisher’s site) | FDA | Approved drug products and therapeutic equivalence evaluations. | Daily |
| NDC Directory (opens the publisher’s site) | FDA | Listing status and DEA schedule by product NDC. | With DailyMed |
| Purple Book (opens the publisher’s site) | FDA | Licensed biological products and reference relationships. | Daily |
| UNII / Global Substance Registration System (opens the publisher’s site) | FDA | Substance identifiers, FDA preferred substance names and other allowed ingredient names. | Daily |
| Drug enforcement reports (recalls), via openFDA (opens the publisher’s site) | FDA | Recall events and the products they affect. | Daily |
| Drug shortages, via openFDA (opens the publisher’s site) | FDA | Drug shortage records. | Daily |
| REMS@FDA (opens the publisher’s site) | FDA | Risk Evaluation and Mitigation Strategy programs and the products they cover. | Daily |
| Drug Safety-related Labeling Changes (opens the publisher’s site) | FDA | FDA-designated safety labeling changes. | Daily |
| FDA SPL terminology (opens the publisher’s site) | NCI Enterprise Vocabulary Services | Standard terms and codes for dosage form, route, units and DEA schedule. | Quarterly |
| MeSH (opens the publisher’s site) | NLM | Chemical structure terms within FDA pharmacologic-class references. | With DailyMed |
| LOINC (opens the publisher’s site) | Regenstrief Institute | Label section names and codes. | With DailyMed |
- DailyMed (opens the publisher’s site)National Library of Medicine (NLM)Prescribing labels (SPL), label set IDs, products, packages and NDCs, FDA pharmacologic classes and billing units.Updated Daily
- RxNorm (opens the publisher’s site)NLMDrug identifiers (RxCUIs), names and RxCUI history.Updated Monthly
- Orange Book (opens the publisher’s site)FDAApproved drug products and therapeutic equivalence evaluations.Updated Daily
- NDC Directory (opens the publisher’s site)FDAListing status and DEA schedule by product NDC.Updated With DailyMed
- Purple Book (opens the publisher’s site)FDALicensed biological products and reference relationships.Updated Daily
- UNII / Global Substance Registration System (opens the publisher’s site)FDASubstance identifiers, FDA preferred substance names and other allowed ingredient names.Updated Daily
- Drug enforcement reports (recalls), via openFDA (opens the publisher’s site)FDARecall events and the products they affect.Updated Daily
- Drug shortages, via openFDA (opens the publisher’s site)FDADrug shortage records.Updated Daily
- REMS@FDA (opens the publisher’s site)FDARisk Evaluation and Mitigation Strategy programs and the products they cover.Updated Daily
- Drug Safety-related Labeling Changes (opens the publisher’s site)FDAFDA-designated safety labeling changes.Updated Daily
- FDA SPL terminology (opens the publisher’s site)NCI Enterprise Vocabulary ServicesStandard terms and codes for dosage form, route, units and DEA schedule.Updated Quarterly
- MeSH (opens the publisher’s site)NLMChemical structure terms within FDA pharmacologic-class references.Updated With DailyMed
- LOINC (opens the publisher’s site)Regenstrief InstituteLabel section names and codes.Updated With DailyMed
Updated is how often we bring in new data from the publisher.
Source dates
Each response identifies the data it used in the X-Data-Snapshot header. Its meta.sources lists the contributing sources with two dates where known: data_as_of, the publisher’s own last-updated or release date (or the day we fetched it when the publisher states none), and retrieved_at, when we last fetched it. X-Data-As-Of gives the oldest data_as_of. These dates describe the data behind the answer and do not promise that a publisher has no newer data.
Attribution and notices
No source publisher, including NLM, FDA, NCI or Regenstrief, sponsors or endorses EntropyAPI.
NLM. This product uses publicly available data courtesy of the U.S. National Library of Medicine (NLM), National Institutes of Health, Department of Health and Human Services; NLM is not responsible for the product and does not endorse or recommend this or any other product.
RxNorm. RxNorm and the terminology derived from it are built from the UMLS Metathesaurus, release 2026AA, and the RxNorm full release of 2026-08-03. RxNorm content is provided under a UMLS Metathesaurus license from NLM. If you redistribute RxNorm content beyond use within your own application, you are responsible for complying with NLM’s terms: https://www.nlm.nih.gov/research/umls/rxnorm/docs/termsofservice.html (opens the publisher’s site)
NCI. Dosage-form, route, unit and schedule terms use codes from the subsets that NCI Enterprise Vocabulary Services publishes for FDA SPL, which are drawn from the NCI Thesaurus and licensed under Creative Commons Attribution 4.0 International (CC BY 4.0): https://creativecommons.org/licenses/by/4.0/ (opens the publisher’s site)
LOINC. This material contains content from LOINC (http://loinc.org). LOINC is copyright © Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license. LOINC® is a registered United States trademark of Regenstrief Institute, Inc. http://loinc.org/license (opens the publisher’s site)
If you display or redistribute response data, keep the attributions shown here. See section 7 of the Terms of Service.