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DBL%20Hendrix%20small.png College chemistry, 1983

Derek Lowe The 2002 Model

Dbl%20new%20portrait%20B%26W.png After 10 years of blogging. . .

Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases. To contact Derek email him directly: Twitter: Dereklowe

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September 19, 2002

More Fun With Patent Expirations

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Posted by Derek

Sometimes I think I should write some sort of script to insert that headline automatically. Not that I want the site to become "Patent Wrangling News," but that's where the action seems to be these days. (If you don't have the new drugs, then fight over the old ones, I guess.)

There's one of these that I haven't talked about yet that could be coming to a decision soon - AstraZeneca versus a host of generic companies, fighting over Prilosec (omeprazole.) (The Wall Street Journal also covered this issue in its "Heard on the Street" column on September 10.)

"Who cares?" might be the first reaction. Omeprazole's off-patent anyway, right? That's why AZN's been trying to convince everyone to take Nexium instead - for the millions who shouldn't take a lower-cost drug that works just fine. All that's true (or my firmly held opinion, in the last clause,) but this case could turn around and affect Nexium as well.

While omeprazole, as a chemical substance, is no longer covered by a patent, there are some formulation patents are the subject of litigation. That's because just taking the compound by itself won't do anyone much good, because it's unstable to stomach acid. AstraZeneca claims (in a patent that won't expire until 2007) to have invented a proprietary coating technology that allows the pill to make it to the small intestine.

The thing is, acid-resistant (enteric) coatings are no big deal in the drug industry, which is just the point that Andrx and several other companies are trying to make. They say that they have an equivalent coating which nonetheless doesn't infringe AZN's patent. "Equivalent" is a key word here, because if the generic behave differently, then it's not really a generic, is it? Andrx would have a new formulation on their hands, and would have to do more extensive testing to get FDA approval. Meanwhile, AstraZeneca is making their coating technique sound like it's the most complicated thing next to an interstellar warp drive, and about as easy to discover.

There's also a manufacturing patent on the same sort of technology. While AZN claims that several generic companies are infringing the first patent, Andrx is the lone defendant in the manufacturing fight. Needless to say, if Andrx wins on the first point but loses on the second, they'll still be stuck. You can't make money off a drug if you can't legally manufacture it. This has all been going on since late last year, and rulings are expected Real Soon Now.

Reversals for AstraZeneca could lead to trouble for Nexium, because the same formulation is used for that one, too (as you'd expect.) Nexium is, as the world should know, merely one pure optical isomer from the racemic mixture that is Prilosec. AZN's position is that the two substances are as different as asphalt and chocolate mousse, and that their separate patents on the optically pure form are as solid as can be. But if the first Nexium firewall (the formulation) is breached, the generic companies may attack the chemical substance itself.

What are the chances? This issue is being fought out in several cases. In Europe, the EPO seems to have clearly stated (as much as that phrase can apply in patent law) that a known racemate doesn't necessarily affect the novelty of the two optical isomers it contains.

But novelty is only one component of patentability. Showing a inventive step can be tricky, because it's widely assumed that one isomer is going to have more biological activity than the other one. It's been held that "an enhanced effect cannot be adduced as evidence of inventive step if it emerges from obvious tests." Now we start arguing about what "obvious" is, and it's just another day in the life of an intellectual property lawyer. Challenges in the US, where single optical isomers have been patented frequently, might well take this "lack of inventive step" tack.

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