Why published patent-expiry lists disagree, and how to check a date yourself

The symptom

Look up a well-known product and you will find one site giving European expiry in 2028, another 2030, a third 2031, and a company annual report saying 2033. Several of these are produced automatically from patent databases; some are copied from each other; a few are right for a question you were not asking.

Six reasons the lists diverge

1. US dates presented as global. Most freely available lists are built for the US market and quote the US compound patent plus its term extension. Europe’s dates come from different filings and a different extension mechanism and can be years apart in either direction.

2. Patent expiry versus SPC expiry. A list that reads the patent register gives the 20-year date; a list that reads the SPC register gives up to five years more; a list that knows about the paediatric extension gives six months beyond that. All three are “the expiry”.

3. Which patent. Some lists take the compound patent, some the latest patent in the family (a formulation patent expiring in 2035 says nothing about when the molecule is free), some the earliest. Without saying which, the year is meaningless.

4. Which country. European SPCs expire on slightly different dates in different countries, and were granted in some and not others. A list with one European date has picked a country or averaged.

5. Litigation and correction. Patents are revoked, SPCs fall with them, expiry dates are corrected after court rulings on how to count. Static lists do not update. Dapagliflozin’s UK SPCs still show a 2028 expiry on many lists a year after they were held invalid.

6. Regulatory exclusivity ignored or conflated. Data exclusivity and market protection are separate clocks; some lists silently use them, some ignore them, and a few present a regulatory date as a patent date.

How to check a date yourself

For one product in one country, this takes about half an hour with the registers:

1. Identify the basic patent. The compound patent is usually named in the SPC entry; start from the national SPC register (UK IPO, DPMA, INPI and so on) rather than the patent register.
2. Read the SPC entry. Status (granted, in force, lapsed), expiry date, any paediatric extension or application for one.
3. Check the patent’s status. In force, or revoked or amended by a court; the national register and the court’s own site.
4. Find the first EU authorisation date (Community Register for centralised products; national registers otherwise) and add eight and ten years.
5. List the secondary patents still in force in that country and ask whether your product falls inside them.
6. Write the result down with its sources and the date you checked. A date without a source is the next item on someone’s list of wrong dates.

Repeat per country. The dates will differ, and that is the answer, not an error.

When a list is good enough

For a first screen of a long portfolio, a list is fine as long as you know which of the six questions it answers and you treat it as a hypothesis. For a decision that costs money, go to the registers, or to someone who maintains them product by product and country by country. That, rather than a cleverer list, is what MPA Search is.