The National Drug Code (NDC) is a gremlin in the works of pharmacy

The National Drug Code, or NDC number as it’s affectionately called in pharmacy, is a set of numbers used to uniquely identify “human drugs and biologicals“. Every pharmacist is familiar with the NDC number, but if you’re not it’s basically a  unique number assigned to each package of medication. It’s an 11 digit number in a 3-segment format, i.e. XXXXX-XXXX-XX.

The first segment consists of five digits and indicates the manufacturer of the drug. The second segment is four digits used to identify the medication and strength. And the final segment of two digits represents the package size.

Here’s a basic example: NDC number for Diovan (valsartan) 80mg capsules is 00083-4000-41.

The 00083- identifies the manufacturer, in this case Novartis Pharmaceuticals.

The -4000- identifies the drug, in this case 80mg valsartan (Diovan) capsules.

The -41 identifies the package size, in this case 4000 count bottle.

If you’d like to entertain yourself for hours looking up NDC numbers feel free to do so by going to the FDA website and using the NDC directory.

The idea of the NDC number appears like a good idea on the surface, but it can create a lot of problems when you have to use these numbers to identify medications within any type of organized system like BCMA. The problem stems from the sheer number of NDC numbers in the wild. Imagine all the drug manufacturers making drugs, then multiply that by the number of drugs made by each manufacturer, then multiply that by the number of different package sizes available for each drug made by each manufacturer, and so on. And remember, many generically available medications are often available from more than one manufacturer. To get a better idea of what I’m talking about go to the NDC directory and search for ‘acetaminophen’. Get the picture?

The NDC number is commonly encoded in the barcode of a majority of unit dosed and bulk medications. Thus it makes sense that the NDC number is the primary method for identifying a medication when using any type of barcode scanning to administer medications at the point of care. Problems arise when the NDC numbers become obsolete, or the manufacturer changes their NDC, or the manufacturer stops making the drug, or a different manufacture starts making the same drug, or the packaging changes, and so on and so forth. This creates a cumbersome system of cross-referenced “crosswalks” in many healthcare systems, including BCMA, pharmacy information systems and finance. Not only can it become difficult to maintain these crosswalks over time, it can be time consuming and is fraught with human error. One error that I’ve seen more than once is when an NDC number gets “taught” to the wrong medication. The system isn’t smart enough to know that you messed up, it only does what it’s told.

I’ve always been curious why the middle four digits of the NDC number are different for the same drug depending on the manufacturer or re-packager. For example:

Capoten 25mg tablets from E R Squibb NDC# 00003-0452-51

Capoten 25mg tablets from Cardinal Health 55154-3707-*7

Capoten 25mg tablets from PDRX Pharmaceuticals 55289-*506-01

Why not just use the same middle four digits to identify the drug entity as 25mg captopril tablets? Why not have the same four digit number tied to only captopril 25mg tablet until the end of time? I don’t know. Maybe someone can explain that to me.

With all the difficulty surrounding the use of NDC numbers for medication identification, some people have proposed using an alternative system such as RxNorm. I’ve written about RxNorm before and think the structure of it is pretty cool, but the utility of it to replace NDC numbers as a unique identifier is not immediately obvious to me. The nomenclature can become pretty complex. I have friends that are pretty high on RxNorm and I’m hoping to sit down with them at ASHP Midyear in December and have them walk me through their thought process to better understand where RxNorm might fit in. Until then I will remain skeptical.

Unfortunately there isn’t a quick fix to the problem as the NDC number is firmly entrenched in pharmacy culture. One thing is for certain however, the NDC number has outlived its usefulness and is on the brink of causing more harm than good. I hope someone has something already on the drawing board because it’s a little late in the game to have to start from scratch at this point. I’m just sayin’.

15 thoughts on “The National Drug Code (NDC) is a gremlin in the works of pharmacy”

  1. Another problem we’ve found with NDC numbers is that they are are also sometimes given to different form factors of medications based on your nomenclature which can create problems in an automated dose dispensing system. Because packaging vendors use the NDC as a unique key to the geometry of the pill to set up the dispensing device or cannister – a change in medication form which does not change NDC can create an opportunity for error. We encourage users of automated dose packaging systems to always test their cannisters every time they fill.

  2. @Carla – Yep, I can relate to that issue as well. I’m sure we’re not the only facility using automated packaging equipment that have a canister graveyard. It’s especially frustrating when, as you elude to, the change in tablet geometry isn’t noticed until it’s too late.

  3. The NDC is still the primary method of product identification for most pharmacy management software (dispensing tracking) and for pharmacy claims submission and adjudication. I certainly agree that there are challenges. One you don’t mention, and is arguably less impactful, but certainly an oddity when you are first exposed to NDCS, is the insertion of a leading zero in the “short” section of the NDC to make it fit the 5-4-2 format.

    Also, a point to keep in mind (if my understanding is correct) is that the FDA may assign the “labeler code” (first 5 digits) to a manufacturer, the remaining digits are selected by the manufacturer, and is merely “registered” with the FDA.

    I would say that a standardized product identifier that is NOT manufacturer or package size specific would be helpful here. RxNorm may help, but other options include GCN or GPI from FirstDataBank or Medispan. If this information were your “cross-walk” (or even better, embedded in barcodes) you could identify the same product across manufacturers or package sizes. One of these non-manufacturer-and-package-size-specific coding methods is how payers often determine pricing, so that no unintended payment variances are introduced (when manufacturers “manipulate” the benchmark pricing like AWP or WAC).

    @Carla – Some manufacturers will change their NDCs when they alter the composition, size, shape, color, etc of their products, but many (especially generic manufacturers) do not. The reasons for changes vary, but often in the generic space, contract manufacturers are involved, and so if a generic “manufacturer” (who may not be actual company producing the product) changes subcontracted “contract manufacturer” then the size, shape, color and other properties will likely change as well. Some manufacturers are more “stable” in this area than others.

  4. @Brian – Thanks for the commentary. You bring up a couple of excellent points regarding the leading zero and the use of a GCN number. I do like the use of the GCN, but have run into problems with injectable medications at times. Definitely worth further discussion though. I always forget about the GCN number. Thanks for bringing that up.

  5. FDA only recognizes a 3 segment, 10 digit NDC # in the configuration: 4-4-2, 5-3-2, and 5-4-1. The 11 digit is a derivative of the standard used by Medicare and a growing number of health plans in claims processing.

  6. Yes there’s also the 10 digit number. But insurance plans don’t recognize them. Trying to locate the 11 digit equivalent is nightmarish, if even possible for the layman. All of this is an excellent example of why having the US Government involved in the medical profession is a huge mistake.

  7. @Ray
    Re govt involved;

    Right. Cause clearly the industry does peachy on its own standards. Take EMR interoperability as a shining example.
    But you can always formulate your own standard and sell it of course.

  8. Hi,
    I have a quick question.

    Can the pharmacy locate the quantifier for any medication, Eg : 80 ml bottle from a NDC code?

    If FDA uses only 10 digit, does the prescribing provider should also be using a 10 digit NDC for prescribing medications or still a 11 digit will be accepted by the pharmacy systems?

  9. Sure thing. Converting an NDC from a 10-digit to an 11-digit format requires a strategically placed zero, dependent upon the 10-digit format. The 10-digit formats can be 4-4-2 5-3-2 5-4-1. The 11-digit NDCs are 5-4-2. Just Google 10-digit NDC and you’ll find better explanations than mine. You can also go rummage around the FDA’s website for more information on NDC numbers (


Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.