LIPITOR GIVES RANBAXY HEARTACHE

Lipitor gives Ranbaxy heartache

News of the decision in the decision of the Court of Appeal for England and Wales in Ranbaxy UK Ltd v Warner-Lambert; Arrow Generics [2006] EWCA Civ 876 on 28 June has been trickling through the system, but the decision of Lords Justices Chadwick, Jacob and Neuberger has not yet been BAILII'd. The IPKat found the summary on subscription-only service Lawtel quite helpful though.

Warner Lambert was the owner of two patents (633 and 281) for atorvastatin, a cholesterol synthesis inhibitor (better known as LIPITOR). Patent 633 covered two structural formulae (I and X) for an enantiomer. According to Ranbaxy it was common in organic chemistry to use the structural formula of a single enantiomer to denote the racemate (basically the 'left-handed' form) or 50/50 mixture of two enantiomers of a chiral molecule. Since the racemate was to be considered as a distinct compound from either of the two enantiomers that were found in it, Ranbaxy said that the specification made it clear that the compound with which it was concerned was the racemate and that, in its context, formula I was being used to refer exclusively to the racemate. Since the claim was limited to the racemate, Ranbaxy's enantiomer did not fall within it. According to Pumfrey J, 633 covered both the racemate and the individual enantiomers. However, he also held that 281 was anticipated by a prior co-pending application and was obvious over a prior published international application.

Ranbaxy appealed against the refusal to grant a declaration of non-infringement of 633; meanwhile Warner-Lambert cross-appealed against the finding that 281 was invalid. The Court of Appeal dismissed Ranbaxy's appeal, holding as follows:

* The skilled reader of the patent would know that the enantiomer in issue was the form which had most or all of the pharmaceutical activity. He'd expect the patentee to know that too.

* There was simply no rational basis for supposing that the patentee would want to exclude the pure enantiomer which, as he would know, was the substance that really mattered.

* Although the actual drawing of figure I and of figure X showed just the enantiomer it was common ground that, in practice, a figure showing that structure might mean its racemate and the judge had held that, in the context of the patent, figure I would have been understood to show the racemate. However there was no rational reason why the figure should mean only the racemate in the context of the patent and there was no convention that such a figure could not mean both the racemate and/or either enantiomer.

* The unpublished earlier co-pending application explicitly disclosed that one of the things that could be made was the single enantiomer of the acid and it was that acid which could be used make the calcium salt. Since that way of carrying out the teaching of the earlier patent would necessarily infringe the later claim, that claim was invalid as lacking novelty.

The IPKat is pleased that the Court of Appeal has spelled out a clear message on the status of racemates; he awaits sight of the judgment before he can say whether there's anything else of pressing legal interest in it.