Ranbaxy UK Ltd & Anor v Warner-Lambert Company

Patent claims must be construed from the standpoint of the skilled person, giving proper weight to the language used while avoiding over-meticulous analysis of grammar and punctuation. Context and common general knowledge may establish that a structural formula denotes both a racemate and its individual enantiomers where the specification makes that meaning clear. Anticipation requires a clear disclosure or clear instructions leading inevitably to the claimed invention; a direction capable of infringing implementation is insufficient. An optional disclosure remains a disclosure. In assessing obviousness, routine resolution of a racemate and routine screening of conventional pharmaceutical salts may make a selected enantiomeric salt obvious.

Ranbaxy sought a declaration that its proposed atorvastatin calcium product would not infringe European Patent (UK) 0247633. Ranbaxy and Arrow also sought revocation of European Patent (UK) 0409281, which claimed atorvastatin calcium, on grounds of anticipation and obviousness.

The court considered the construction of stereochemical formulae, anticipation by an earlier international application, the effect of optional language, selection patents, and the appropriate approach to obviousness.

1. Construction of ’633. The modern approach, as summarised in [2004] UKHL 46, requires the court to ask what the skilled person would understand the claim language to mean in context. Carefulness must not become over-meticulousness. The skilled addressee was a medicinal chemist with organic-synthesis expertise.

2. The specification’s reaction schemes produced racemates, its examples compared racemates, and its common general knowledge indicated that the active component would probably be a single enantiomer capable of routine resolution. In that context, formulas I and X denoted the racemate while also covering its individual enantiomers. Claim 1 of ’633 therefore covered both the racemate and the individual enantiomers. The declaration of non-infringement was refused.

3. Anticipation of ’281. Following General Tire v Firestone, [1972] RPC 457, a prior disclosure must clearly describe, or clearly instruct the skilled person to make, something falling within the claim. The claimed invention must be the inevitable result of carrying out the prior teaching. A mere signpost is insufficient.

4. The ’598 application expressly identified the relevant 4R,6R enantiomer and disclosed hydroxy acids and pharmaceutically acceptable salts, including calcium salts. Routine resolution did not prevent anticipation. Claim 1 was anticipated.

5. The description of conversion to a salt as optional still disclosed that conversion. Claim 2 was therefore also anticipated. The court rejected the contrary argument by reference to the reasoning in Gillette v Anglo-American, (1913) 30 RPC 465.

6. Obviousness. The skilled person would routinely resolve the racemate, identify the active open-chain acid, and screen conventional salts for pharmaceutical formulation properties. Selecting calcium from the specifically disclosed pharmaceutically acceptable cations involved no inventive endeavour. Claims 1 and 2 of ’281 were obvious.

7. The court expressed concern that reformulating the objective problem by reference to an advantage discovered or recognised only later could create an artificial finding of non-obviousness. After-discovered advantages were highly unlikely to support inventiveness unless the skilled person could recognise them as implied in, or related to, the initially suggested problem.

8. Ranbaxy’s declaration claim concerning ’633 was refused. The ’281 patent was found invalid for anticipation and obviousness. The court was to hear counsel on the appropriate order if not agreed.