The NDC code is a 10 digit code that is applied to uniquely identify products having a drug registry component. The number is a 3 segment number in terms of its construction and the various components correspond to sections responsible for the label, the product, and the packaging.
The first section identifies the labeler code, is assigned by the FDA and it identifies any manufacturer (including re-packagers or re-labelers) or distributer (under their own name) of the drug or drug-containing material.
The second section identifies the product code which includes the specific strength, dosage form, and formulation for the company.
The third section identifies the packaging code and this corresponds to the package size and type. This part together with the product code is provided by the company filing the NDC application.
In practice NDC codes follow the following convention: 4-4-2, 5-3-2 or 5-4-1, where the second and third parts are determined by the operating convention within each individual company.
In practical terms then, should a packaging size change for the product and if the same product is manufactured in the same location, then the codes would change and a unique code would be required for that packaging configuration/size.
Similarly, if the packaging size was the same but the formulation changed, then the code would also change to a new unique number for that formulation.
Changes in the product which force a change in the label would also trigger a change in the primary code used by the FDA.
So this is a complex process that may require the filing of many systems where a product may have several packaging configurations, several formulations, and several label types.
Guidance through this process is best achieved by employing a pharmaceutical consultant who can objectively steer a clear path through the maze of paperwork and forms to provide a lean process for the most effective and efficient outcome.