Sunday, November 12, 2006

Abbott v. Baxter: CAFC finds anticipation, but still needs a chemistry lesson

Frightening definition of Lewis acid in Abbott v. Baxter?

In the case, plaintiff Abbott was appealing from a judgment of noninfringement of US 5,990,176. Abbott received a determination of invalidity over US 5,684,211 from the CAFC.

The compound at issue was sevoflurane. Sevoflurane degrades in the presence of Lewis acids, compounds which accept electron pairs (e.g., boron trifluoride. Look here for the statement: As a result, any substance that can act as an electron-pair acceptor is a Lewis acid.). The CAFC defined Lewis acids in a curious way: any species with an empty electron orbit [sic: orbital] leading to electron affinity. Here, sevoflurane can give up HF in the presence of Lewis acids. Abbott found that water inhibited the decomposition.

The claim pertained to a composition comprising sevoflurane and a "Lewis acid inhibitor."

In 2001, Baxter filed an ANDA, pursuant to the Hatch-Waxman Act, to market its own version of sevoflurane.

Of invalidity, Baxter argued that Kawai's '211 patent (issued Nov. 1997) disclosed a composition of water-saturated sevoflurane. The district court (ND Ill) did cite to Bristol Myers Squibb v. Ben Venue, 246 F.3d 1368, and focussed its attention on the wording "for the same purpose." The '211 patent concerned an "intermediate" step in the manufacture of sevoflurane.

The CAFC first cited Titanium Metals v. Banner, 778 F.2d 775, and then provided a list of cases showing a new use of an old composition is not patentable. [For an earlier discussion of "new use" see an earlier IPBiz post.]

The CAFC noted BMS v. Ben Venue applies ONLY to process claims.

IPBiz: Electron affinity is defined as the energy given off when a neutral atom in the gas phase gains an extra electron to form a negatively charged ion. The interrelation between "Lewis acid" (which involves acceptance of pairs of electrons by a molecule) and electron affinty (which involves addition of an electron) by the CAFC is puzzling.


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