Now you see them, now you don’t: Catch those expiration date issues before your patent or exclusivity disappears!

This blog entry is not so much about Orange Book Supplement 5 (May 2019) (see the end of this posting for that). Instead, it is a warning about the ramifications of not seeing expiration date issues, regardless of whether they were created by you or the FDA, in the Orange Book.

What brought this issue to my attention?
I was making needed changes to the computer code that generates the Orange Book Archive™ (“OBA”) section of my Orange Book Companion®(“OBC”). Over the last few years, whenever the FDA made changes to its raw data files I would take the lazy route of making minor changes to the computer code which would make the new data files look like the old data files. In that way I did not have to make major changes to the downstream computer code.

For my update of the OBA to include 2018 expirations I decided to bite the bullet and make the major revisions that would allow my code to use the FDA’s current data file format directly. No more retrofitting of the new data files into the old code. It was during my testing of the new code that I discovered a couple cases of disappearing patents and exclusivity.

The case of the disappearing exclusivity!
The first issue I discovered was the disappearance of an exclusivity (M-90) for Roche’s TAMIFLU®. How did I discover this? A nice feature of my computer code is that it will combine the patent and exclusivity information of multiple strengths of a drug into a single table if all of the patent and exclusivity information for those strengths is identical. That saves my OBC subscribers from having to visually compare several Electronic Orange Book tables (one for each strength) to see if there are differences. My computer code does that for them.
While testing my code updates I randomly selected OBA pages to look for issues. One of those pages contained products whose trademark started with “T.” When I scrolled through that page I found three tables for Roche’s TAMIFLU®. One table was for the 75mg strength. It had several more exclusivities than the later-approved 30 and 45mg strengths, so a separate table for the 75mg strength was appropriate.

But why were the 30 and 45mg strengths in separate tables? At first glance I did not see a difference. I then studied the two tables more closely and found a one character difference: the expiration date of the M-90 exclusivity ended in a “3” for the 45mg strength, and ended in a “0” for the 30mg strength. The month and day was the same: February 22. My computer code saw this and broke the two strengths into separate tables. This discrepancy created a three-year difference in the expiration dates. Here is a screenshot from the printed Supplement 2 (February) of the 2010 Orange Book showing the addition of the M-90 exclusivity and the discrepancy in the expiration date for the 30mg (003) strength:


Where did this three-year difference in the M-90 exclusivity come from?
I found in the Drugs@FDA database that the label change described in the M-90 exclusivity code was approved on February 22, 2010 for all strengths. So the correct expiration date of February 22, 2013 was listed for the 45mg strength (as well as for the 75mg strength). Somehow, however, the approval date of the label change was entered into the Orange Book for the 30mg strength. 

So what does this have to do with a disappearing exclusivity?
The FDA removes expired patents and exclusivities from the Orange Book each year. So when the 2011 Orange Book (Volume 31) was published it did not contain the M-90 exclusivity for the 30mg strength of TAMIFLU. Apparently, in the eyes of the FDA the M-90 exclusivity for the 30mg strength had expired on February 22, 2010. Poof! So be vigilant. The accuracy of the patent and exclusivity listings for each strength of a drug has to be confirmed separately.

I will report on the disappearance of an extended patent for one strength of a drug in a future posting. I am waiting for some feedback from the NDA holder.

So, what was new in the Orange Book in May
Nothing too exciting or controversial in the May (Supp. 5) update. There were 32 new patents listed. Three patents were delisted. One of those, 9,060,976, which is listed for Perdue Pharma’s OXYCONTIN®, had a divided delisting. The ‘976 patent was delisted for the 15mg through 80mg strengths while the patent remains listed for the 10mg strength with a newly added “Delisting Requested” flag.


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