Purification of a Compound may be Obvious

Aventis Pharma Deutschland GmbH v, Lupin, Ltd., [2006-1530, -1555](September 11, 2007)[LINN, Mayer, Robertson] The Federal Circuit reversed summary judgment that the a generic version of ramipril infringed Aventis’s U.S. Patent No. 5,061,722, concluding that the subject matter would have been obvious.
SIGNIFICANCE: Purification of a compound of known benefit or effect may be obvious
BRIEF: After review the scope of the prior art, the Federal Circuit examined obviousness, noting that even after KSR it remains necessary to show “‘some articulated reasoning with some rational underpinning to support the legal conclusion of obviousness,’” but such reasoning “need not seek out precise teachings directed to the specific subject matter of the challenged claim.” In the context of chemical inventions, the Federal Circuit noted the “reason or motivation” need not be an explicit teaching that the claimed compound will have a particular utility; it is sufficient to show that the claimed and prior art compounds possess a “sufficiently close relationship . . . to create an expectation,” in light of the totality of the prior art, that the new compound will have “similar properties” to the old. In the context of a purified material, the Federal Circuit said that 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 weight in itself. 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.