Aventis Pharma & King Pharma v. Lupin Ltd. (Fed. Cir. 2007).
Altace is the King/Aventis brand of ramipril – a top-selling ACE inhibitor. The patent claims ramipril formulated “substantially free of other isomers.” The district court found the patent not invalid, but only by a slim margin. On appeal the CAFC reversed – finding the patent invalid as obvious.
Prior Art: One reference (‘944 patent) was filed as a continuation-in-part of an already abandoned patent application. That application was eventually revived, but Aventis argued on appeal that the ‘944 patent should not be awarded the filing date of the parent. The CAFC found this a potentially interesting argument, but refused to hear the argument because Aventis had failed to make the argument at the district court level.
The appellate panel also agreed that the experimental results of a Shering Doctor constituted 102(g)/103(a) prior art because the Doctor had not abandoned, suppressed, or concealed her prior invention.
Obviousness of a Purified Form: The district court, ruling pre-KSR, found the patent nonobvious. On appeal, the CAFC took a different view – finding that the purified form of a known mixture is prima facie obvious if a PHOSITA would have some reason to believe that the mixture derives properties from particular components.
However, if it is known that some desirable property of a mixture derives in whole or in part from a particular one of its components, or if the prior art would provide a person of ordinary skill in the art with reason to believe that this is so, the purified compound is prima facie obvious over the mixture even without an explicit teaching that the ingredient should be concentrated or purified.
The prima facie case of obviousness is especially difficult to rebut where, as here, the potency of the mixture varies directly with the amount of isomer in the mixture.
The court implicitly distinguished this case from Forest Labs — noting that obviousness may be rebutted by showing difficulty in purifying the mixture.
[A] purified compound is not always prima facie obvious over the mixture; for example, it may not be known that the purified compound is present in or an active ingredient of the mixture, or the state of the art may be such that discovering how to perform the purification is an invention of patentable
Reversed, Patent Invalid as Obvious