Atorvastatin : Ranbaxy & Arrow v Warner-Lambert
Mr Justice Pumphrey gave judgment yesterday in relation to the applications by Arrow and Ranbaxy to revoke Warner-Lambert’s patent no UK 0409281, covering atorvastatin in its lactone form and Ranbaxy’s application for a declaration of non-infringement of Warner-Lambert’s patent UK 0247633 (atorvastatin calcium).
The judge decided that Warner-Lambert’s patent UK 0247633 would be infringed by the manufacture or sale, of single enantiomer product - even though the patent only refers to the racemates (containing both enantiomers of the claimed products (eg atorvastatin lactone racemate, atorvastatin racemate sodium)).
The judge revoked Warner-Lambert’s patent UK 0409281 (claiming atorvastatin calcium) on the basis that it was anticipated by WO 89/07598, and that it was obvious given the ‘633.disclosure of atorvastatin racemate sodium.’
‘598, covers, amongst other things, atorvastatin in its lactone form.It also referrs to the calcium salt of the preferred isomer, and gives a preferred enantiomer – the judge said that this was ‘a clear case of anticipation’..
In relation to obviousness of 281, the judge considered that ‘633, which disclosed the sodium salt of the atorvastatin racemate, rendered the patent obvious.He came to this conclusion on the basis that it was common general knowledge that activity would reside in one enantiomer, that the active form was not the lactone but the open chain form and its salts, that it was common practice to carry out a ‘salt screen’ , and that the resolution of racemates was well-established.
The judge thought that there was clear teaching in ‘633 that the lactone racemate may be hydrolysed to produce the acid racemate, the calcium salt being mentioned, and a description being given of the manufacture of the sodium salt.
He felt that the differences between 633 & 281 were obvious. Seven salts were mentioned in 633, and the choice of the calcium salt was not inventive. Work to produce the ‘281 product was routine.
This is an important judgment, not only because of the commercial importance of Lipitor, but also because of the effect it may have on other patents covering enantiomers.
Pfizer (Warner-Lambert’s parent) and Ranbaxy have each said that they will appeal.
A similar case is ongoing in the US.
Do call me if you have questions about the judgment.
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