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Tuesday, 6 March 2007

Baxter v Abbott: insults & degradation

The IPKat brings you a recent decision by the Honourable Mr Justice Pumfrey at the Patents Court, which has been made available on BAILII.

Baxter Healthcare had sought a declaration of non-infringement in respect of EP(UK) 0967975, granted to Abbott Laboratories, together with revocation of the patent under section 72. Abbott's granted patent was directed to sevoflurane (right), a fluoroether anaesthetic composition, and to a method for inhibiting its degradation in the presence of a Lewis acid.

The discovery behind the invention was that a small amount of water added to sevoflurane would effectively neutralise the effects of any Lewis acids present (left: Gilbert Lewis in action). This discovery was extrapolated to addressing the alleged problem of degradation of sevoflurane as conventionally stored in glass containers, where components of the glass could apparently provide Lewis acid sites. Adding water to the sevofluorane would, following this reasoning, prevent degradation.

Abbott attempted to prove the link by adding activated aluminium oxide powder to samples of sevoflurane (described by Pumfrey J as 'insults') in various anhydrous and hydrated forms, results of which were included in the patent specification. They showed that the presence of water reduced degradation caused by the presence of the Lewis acid sites on the oxide surface. What they did not show, however, was whether the problem of degradation actually occurred in practice, but merely that the possibility existed.

Mr Justice Pumfrey found that there was no evidence for any kind of insult anywhere near the level of that in the patent occurring in practice. Also, since many tons of sevoflurane had been sold for many years, it was a safe bet that the material was not degraded in normal use, but was stable. Abbott could not convince the judge that the patent showed what particular level of water would be sufficient to prevent degradation of any given quantity of sevoflurane. This led to most of the claims being found to be invalid for insufficiency.

There was also the problem of a prior art document clearly disclosing a method of making sevoflurane that would inevitably result in a water-saturated sevoflurane composition, being squarely within the claimed invention. Abbott's argument that this result would not be "an anaesthetic composition" as required by the claims did not convince the judge.

The patent was also found to be invalid due to added subject matter and all of the claims were in any case anticipated on grounds of prior public use.

Given the varied mostly fatal defects, the IPKat wonders how this patent came to be granted in the first place, let alone how it managed to get through oral proceedings and a lengthy opposition procedure at the European Patent Office (an appeal is still pending at the time of writing).

Merpel points out that one small clue might be the generally well-respected 'problem and solution' approach favoured by the EPO, which appears to have been used by Abbott to convince the Board into dismissing the opposition, since the alleged problem of degradation was apparently solved by the invention. With this logic, Merpel adds, perhaps the technique of thinking up a non-existent problem and solving it by providing a solution available in the prior art could be useful for other problematic EP applications.

1 comment:

Peter Groves said...

I think the word "insult" is used in chemistry to denote subjecting something to extreme conditions - see for example http://pearl1.lanl.gov/external/Research/chem_dynamics.htm. It's not just Pumphrey J making it up, it's him showing his erudition. (But I'm not qualified to say whether it's the correct usage!)

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