H Lundbeck AS v Norpharma SPA & Ors

A patent claim is assessed according to the language used, construed purposively in its technical context. A generic or silent disclosure does not anticipate a specific claimed range unless the subject matter is disclosed, expressly or implicitly, and enabled. The court rejected the proposition that a broad disclosure anticipates an overlapping narrow range merely because the skilled person would seriously contemplate working within the overlap.

For obviousness, the statutory question remains whether the claimed invention was obvious to the skilled person. A structured analysis is a helpful guide but cannot replace that question. A process claim may be obvious where the skilled industrial chemist would undertake routine investigation, without invention, to substitute a less hazardous reagent and use ordinary atmospheric-pressure equipment.

H Lundbeck A/S sought revocation of European Patent (UK) 1 118 614, owned by Infosint S/A, concerning a process for making 5-carboxyphthalide, an intermediate used in making citalopram. Infosint counterclaimed for infringement against Lundbeck and related companies.

The issues included novelty over a Danish patent application, obviousness over publications by Forney, insufficiency of a claim directed to making citalopram, infringement by several manufacturing processes, the prior-user defence under section 64 of the Patents Act 1977, and the effect of delayed registration of the assignment under section 68.

1. Construction. The claims were construed purposively. An open reactor meant one vented to atmosphere through suitable equipment, and a not-pressurised reactor meant one operating at or close to atmospheric pressure. The upper limit of 145°C meant 145°C, subject to the ordinary precision of a whole-number temperature. However, the claim did not require the reaction to remain within the stated range throughout the whole process. Making some 5-carboxyphthalide within the range was sufficient, subject to any possible de minimis question not decided.
2. Novelty. Section 2 of the Patents Act 1977 required disclosure and enablement. The Danish application disclosed oleum but was silent as to its sulphur trioxide concentration. Silence could not be converted into disclosure of a range from 1% to 99%, and claim 1 was not anticipated.
3. Obviousness. Applying the statutory test, and using the Pozzoli structure as a fact-finding aid, the skilled industrial process chemist starting with the Forney papers would naturally consider oleum as a less hazardous alternative to liquid sulphur trioxide. The papers gave no warning against 20–30% oleum and showed robust reaction conditions. Trying such oleum in an open, unpressurised reactor was routine process investigation and involved no invention. Claim 1 was therefore obvious.
4. Claim 22. A skilled person seeking to put the citalopram process in the 513 application into effect would need a method of making 5-carboxyphthalide. Standard reference works would lead inevitably to Forney 1 and then to the other Forney material. Claim 22 was obvious over the 513 application and Forney. The alternative aggregation argument was not decided.
5. Insufficiency. Claim 22 was not insufficient. It claimed the general principle of using 5-carboxyphthalide made by the claim 1 process to make citalopram. One disclosed method was enough because the skilled person could reasonably expect the invention to work with processes producing citalopram from that intermediate.
6. Infringement and defences. Had the patent been valid, certain processes infringed claim 22, including the CF Pharma, pre-26 October 2009 Ramdev and Jet processes. Other processes fell outside the claims because of temperature, pressure or oleum concentration. Section 64 gave a practical right to continue substantially the same pre-priority act, but did not extend to materially different two-pot processes or to escitalopram where only racemic citalopram had previously been imported.
7. Section 68. Registration of an assignment of a granted European patent at the EPO was not registration under the Act. The assignment had to be registered on the UK register. The section 68(b) exception failed because registration was practicable and had not been achieved within the statutory period. If infringement had occurred, damages before 29 April 2006 and costs on and after that date would have been limited.
8. Disposition. The patent was invalid: claim 1 was not anticipated by the Danish application but claims 1 and 22 were invalid for obviousness. Claim 22 was not insufficient.