Currently, drug products are identified and reported using a unique 10-digit, 3-segment number called the National Drug Code (NDC) (21 C.F.R. §§ 201.2 and 207.35). The NDC assumes one of the following configurations: 4-4-2, 5-3-2, or 5-4-1. Under the original system, the NDC number contained nine characters, either as numbers or letters. In the 1970s, however, it was changed to a 10-digit number and the original 9-character codes previously assigned to products received a leading zero. The first segment of the code is assigned by the FDA and identifies the manufacturer or distributor (labeler code). The second segment of the code number identifies a specific strength, dosage form, and formulation for a particular firm (product code). The third segment identifies package size and types (package code). The firm supplies the product and package codes.

Although the NDC is 10 digits, the standard for billing and claims submissions is an 11-digit NDC. This is accomplished by inserting a leading zero into one of the segments. The zero is added to the beginning of the first segment if it is four numbers, added to the beginning of the second segment if it is three numbers, or added to the beginning of the third segment if it only has one number.

On July 22, 2022, FDA announced a proposed rule (87 Fed. Reg. 44038), Revising the National Drug Code Format and Drug Label Barcode Requirements, that is intended to minimize the impact of FDA running out of 10-digit national drug codes (NDCs) by adopting a single, uniform 12-digit format for FDA-assigned NDCs. The FDA is proposing to change the NDC to 12 digits in length with three distinct and consistent segments and one uniform format. The proposed configuration would be 6-4-2. Additionally, the proposed rule would also revise the drug barcode label requirements, allowing for the use of either linear or nonlinear barcodes, as long as certain standards were met.

The presence of the NDC number on the label or labeling does not indicate that a drug has received an approved NDA. The FDA assigns the number simply for identification purposes. It has proved invaluable for facilitating the processing of third-party prescription drug claims and for distributing products among manufacturers, wholesalers, and pharmacies. The FDA maintains an NDC directory at https://labels.fda.gov.