Friday, January 18, 2019 T 1085/13 - Purity of a compound is not the inevitable result of a prior art preparation method

If the prior art already discloses a (low-molecular) chemical compound having a certain degree of purity and a method for its manufacture, does this imply an implicit disclosure of the same compound having a higher purity - thus prohibiting later claims to the compound defined by a certain higher degree of purity?

Previously, the Examining Division had refused the sole request of the Applicant, pertaining to a chemical compound defined in claim 1 as "Amorphous Lercanidipine Hydrochloride having a purity of at least 99.5% determined by HPLC analysis and containing less than 0.5% of crystalline Lercanidipine Hydrochloride". Relying inter alia on T 990/96, the Examining Division argued that the disclosure of amorphous Lercanidipine Hydrochloride ("LH") and its manufacture in prior art document D1 already had made available this compound to the public in the sense of Article 54 EPC in all desired grades of purity, and the claimed degree of purity could therefore not render the claims novel.

Departing from T 990/96 and subsequent cases including T 0728/98, the present Board of Appeal held that, in line with in particular decisions G 2/88 and G 2/10, in order to conclude a lack of novelty, there must be at least an implicit disclosure in the state of the art of subject matter falling within the claimed scope. Such an implicit disclosure would mean no more than the clear and unambiguous consequence of what is explicitly mentioned in the prior art. Thus, the skilled person, using his common general knowledge, would understand a feature as implicitly disclosed in a prior-art disclosure only if it is the clear and unambiguous consequence, and hence the inevitable result of what is explicitly derivable from said prior art disclosure.

In the present case, it was demonstrated (in a report filed during examination) that a purity falling within the claimed range is not the inevitable result, and thus not an implicit feature, of the preparation method taught in D1. The question whether (further) purification methods required to reach the claimed purity were within the common general knowledge of those skilled in the art was not considered relevant to novelty, but rather a matter to be considered in the assessment of inventive step.

The Board found that having regard to both the common general knowledge and the state of the art, no purification techniques were available prompting the skilled person to solve the technical problem of providing amorphous LH having a higher purity.

Accordingly, amorphous LH having the claimed degree of purity was found to be novel and inventive.