Mapping U.S. FDA National Drug Codes to Anatomical-Therapeutic-Chemical Classes using RxNorm

For analyzing prescription datasets, usually one wishes to identify drugs by classes, rather than by U.S. FDANational Drug Codes. We demonstrate how to utilize the NLM RxNorm online API to map NDCs to WHOAnatomical-Therapeutic-Chemical classes, and present statistics and caveats of mapping 71,309 NDCs found inMedicare Part D claims from 2006 to 2013 and 134,580 NDCs found in a commercial all-payer claims dataset fromPartners Healthcare from 2011 to 2012. Garbage removed from the submission United States’ National Drug Codes (NDC) are 10 or 11-digit codes assigned by the U.S. Food and DrugAdministration to uniquely identify a drugs in the U.S. market by labeler (manufacturer, distributer or re-packager),product (drug[s], strength[s], dosage[s], and form such as pill or vial), and packaging (e.g. 100 capsules). by the combination of labeler (manufacturer, distributer or re-packager), product (drug[s], strength[s], dosage[s], anddosage form such as pill or vial), and packaging (e.g. 100 capsules). The regulation governing the NDC assignmentprocess is such that the FDA mandates only the labeler digits, while the product and package digits are chosen at willby the labeler. Moreover, up until 2017 the regulation explicitly permitted reuse of an NDC after the drug it previouslyrepresented had been out of the market, or expired, for 5 years. Therefore, drug (4 or 5 digits representing manufacturer, distributer or re-packager), product (4 or 3 digits representing drug[s],strength[s], dosage[s], and dosage form such as pill or vial), and packaging (2 or 1 digit representing the package, e.g.100 capsules). The regulation governing NDC assignment is such that the FDA mandates only the labeler digits, whilethe product and package digits are chosen by the labeler. Moreover, up until 2017 the regulation explicitly permittedreuse of an NDC after the drug it previously represented had been expired, or out of the market, for 5 years. Therefore,although the FDA provides official listings of NDCs with details such as The regulation governing NDC assignment is such that the FDA mandates only the labeler digits, while the productand package digits are chosen by the labeler. Moreover, up until 2017 the regulation explicitly permitted reuse of anNDC after the drug it previously represented had been expired, or out of the market, for 5 years. Therefore, althoughthe FDA provides official listings of NDCs with details such as