[2008] EWHC 3070 (Pat)

The Patents Court (Mr Justice Floyd) handed judgment down on 16 December 2008 relating to two patents regarding formulations to achieve slow release of the opioid pain killing drug, oxycodone. The proceedings started with actions by ratiopharm and Sandoz to revoke European Patent (UK) Nos. 722730 (“730”) and 1258246 (“246”) and declarations of noninfringement in respect of pharmaceutical products, developed and manufactured by the Swiss company Cimex AG, which ratiopharm and Sandoz both wished to market. Napp responded to both cases with a counterclaim for infringement, asserting that the patents were both valid and infringed, and which so evolved into a conventional patent action brought by Napp against ratiopharm and Sandoz.

Oxycodone has been in clinical use since 1917, and as the formulation patents have a priority date in 1991, the case is unusual in that there was no patent to prevent the manufacture of a slow release version of the drug before 1991. Ratiopharm and Sandoz denied infringement on a number of grounds, most of which depended on the proper construction of the claims.

The Court referred to a decision of 27 April 2007 of the Düsseldorf District Court in an action on the German designations of the patents in suit against Cimex AG, where an interim injunction was not granted, relying on some of the points argued by ratiopharm and Sandoz in the UK Court and the decision of 19 August 2008 where the Mannheim District Court reached the same conclusion. Although it was felt that these decisions were of considerable persuasive authority, it was felt by the Judge that the German decision attached too much importance to the fact that claim 6 of 730 refers to “the” oxycodone, and so he concluded, differently to the German Court, that it does not contain a requirement that all the oxycodone is within the spheroids (claim 6 states “each spheroid being coated with a film coating which controls the release of the oxycodone or oxycodone salt”).

Specifically, the Cimex product is a tablet formulation which contains embedded in excipients, small particles made up of a number of layers. The core is composed of commercially purchased sugar crystals. The inner layer of oxycodone hydrochloride (83%), hydroxypropyl methyl cellulose (8%) and talc/macrogol (9%) is sprayed onto the sugar core. Next is a polymer layer, or “coating”, which controls the release of oxycodone hydrochloride from the inner layer. The outer layer also contains oxycodone hydrochloride (96%) and hydroxypropyl methyl cellulose (4%) – about 20% of the total weight of the oxycodone in the tablet is actually in the outer layer, i.e. not in the “spheroid”. Thus the Judge concluded that claim 6 of 730, properly construed, is broad enough to cover the Cimex product notwithstanding that 20% of the oxycodone was not in the “spheroids”.

Although ratiopharm and Sandoz contended that the Cimex particles are not granules, and therefore are not “spheroids” within the definition in the patent, the Judge’s approach on construction was to take the particles as granules, stating they are agglomerates of smaller particles albeit including a large central particle as the core. With regard to the claim requirement that the “spheroids compris[ing]e oxycodone or a salt thereof and a spheronising agent.” Napp contended that the hydroxypropyl methyl cellulose in the inner layer is the “spheronising agent,” but the judge found it was not, since the function of the hydroxypropyl methyl cellulose is to act as a binder or matrix for release of the drug at a rate controlled by the polymer layers. It followed that claim 6 of the 730 patent is not infringed, and all remaining claims were dependent on claim 1 (not alleged to be infringed) and claim 6 – it followed that there was no infringement of 730. For similar reasons it followed that claim 4 of 246 is not infringed - the judge also came to the view that on the correct construction of 246, claims 1 and 4 are not infringed because there is a significant amount of oxycodone, the release of which is not determined by the polymer layer. Therefore it was concluded that neither 730 nor 246 are infringed by the Cimex tablets. It was also held that neither patent is invalid for added matter or obviousness, amendments to 246 were allowed, and the condition on which amendments to 730 were applied for did not arise.

The judgment on obviousness is of note, specifically in relation to pleadings of obviousness over “common general knowledge”. The Judge observed that “the time has come when matter which is said to be common general knowledge ought to receive some more formal exposition in advance of the expert evidence stage” - which is likely to be welcomed by many practitioners who have long felt current pleading practice to be unsatisfactory in this regard. Also of note is the Judge’s finding that the limited exceptions to the impermissibility of disclaimers which are not founded on the text of the application for a patent (under the EPO Enlarged Board of Appeal decision in PPG Industries (G0001/03)) do not apply to disclaimers in divisional applications (where Article 54(3) EPC or “accidental” anticipation considerations are not in issue).