Case: Ranbaxy Australia Pty Ltd v Warner-Lambert Co LLC (No 2) [2006] FCA 1787 , (2006) 71 IPR 46 
Outcome: discussed
A little earlier than the decision in Alphapharm [2008] FCA 559 , Young J had considered a similar issue in Ranbaxy Australia Pty Ltd v Warner-Lambert Co LLC (No 2) [2006] FCA 1787 , (2006) 71 IPR 46. One question was whether the formula in claim 1 of the relevant patent claimed only the racemate and not the enantiomers separate from the racemate. The patentee, Warner-Lambert, called, amongst other witnesses, Professor Christopher Easton and Professor Peter Scammells, who gave evidence for Sanofi-Aventis in these cases. The applicant for revocation, Ranbaxy, called, inter alia, Dr Keith Watson, who was called by Apotex, one of the applicants, in these cases. His Honour's findings about common general knowledge (so far as is relevant) were as follows ( Ranbaxy [2006] FCA 1787 , 71 IPR 46 at [113] ): "(7) The biological activity of a racemate in a biological system can be quite different from that of a single enantiomer. The physical and biological properties of a racemate differ from that of an individual enantiomer in various respects: for example, there may be differences in solubility between the racemate and its enantiomers and differences in pharmacological properties. (8) The normal expectation is that there would be one enantiomer that is approximately twice as active as the racemate in terms of its operation in the target biological system. (9) Before 30 May 1986, the skilled team would expect that the R enantiomer was very likely to be the active, or more active, enantiomer, but this could not be known with certainty without isolating and testing the enantiomer. (10) Conversely, it was very likely to be the case that the S enantiomer was inactive, or substantially less active, than the R enantiomer, but this could not be known with certainty until the enantiomers had been isolated and tested. (11) Well before 30 May 1986, it was common general knowledge amongst medicinal chemists that racemic mixtures could be separated into the individual enantiomers by well-known methods of resolution. Indeed, undergraduate chemical students were taught procedures to resolve enantiomers. It was also generally known before May 1986 that enantiomers could be obtained by chiral synthesis. (12) As at 30 May 1986, it was feasible to use resolution or chiral synthesis to obtain a single enantiomer drug. Pharmaceutical companies had produced single enantiomer synthetic drugs either by way of resolution from the corresponding racemic mixture or by way of chiral synthesis prior to May 1986. (13) As at May 1986, it was known that enantiomers could have different biological properties and that it may be desirable to separate and remove the less active enantiomer." 71 His Honour found that the formula did include claims for the enantiomers as such, notwithstanding that there was no reference to them. An important part of his reasoning was as follows ( Ranbaxy [2006] FCA 1787 , 71 IPR 46 at [121] [122] and [128] [129]): "Perhaps the most important background consideration against which the claims of the 981 Patent must be construed is that the skilled addressee would know that HMG-CoA reductase inhibitors, such as the class of compounds referred to in claim 1, are enantiomeric and that one enantiomer is very likely to be more active than the other. The skilled addressee would also know that the biological activity of a racemate will be different from that of the single enantiomers, and that the active or more active enantiomer will be approximately twice as active as the racemate. In these circumstances, confronted by a structural formula in claim 1 that shows relative stereochemistry, the skilled reader would consider that the structural formula was intended to claim both enantiomers, as well as racemic mixtures. I do not think that the skilled addressee would read the structural formula as one that was intended to exclude the more active enantiomer. Reading the specification as a whole, the skilled addressee would discern that the patentee had not isolated the individual enantiomers and that the absolute stereochemistry of the more active enantiomer, and that of the less active enantiomer, had not been defined. The skilled addressee would also know that, while it had not yet been done by the patentee, it was a routine step to obtain the individual enantiomers by resolving the racemic mixture, and that it was also possible to make the individual enantiomers by chiral synthesis. In those circumstances, the skilled addressee would expect, in the absence of a clear indication to the contrary, that claim 1 of the patent was intended to include the more active enantiomer. ... In these circumstances, in the absence of any clear indication or language to the contrary, the skilled addressee as at May 1986 would read claim 1 as encompassing both individual enantiomers, as well as mixtures of them. As Warner-Lambert submitted, it would make no sense to exclude patent protection for the more active enantiomer. The point was well made by Professor Easton in the course of his affidavit evidence when he said that to confine the subject of the 981 Patent to racemic mixtures would exclude the thing (the active or more active enantiomer) that he, and any person working in the field as at May 1986, would know to be the key to the useful activity of the compounds disclosed by the patent. It is not in dispute that structural formula I would be construed by the skilled addressee as including a trans racemate of the compounds of the formula. But there is no reason why the skilled reader would construe the formula as meaning only the trans racemate, thereby excluding both the R-trans and the S-trans enantiomers. In the absence of a clear indication to the contrary, it offends common sense to construe structural formula I in that way." Young J referred to decisions on the same patent in England and the United States which adopted a similar construction. 73 Although the decisions in Alphapharm [2008] FCA 559 and Ranbaxy [2006] FCA 1787 , 71 IPR 46 turned in large measure upon the evidence in each case, a difference in approach can be detected on the question involving the disclosure of enantiomers, with Ranbaxy [2006] FCA 1787 , 71 IPR 46 favourable to the applicants on this issue, and Alphapharm [2008] FCA 559 being neutral. In neither case was there the express reference to enantiomers such as there is in the French and corresponding patents here. The priority dates of the relevant patents are also interesting when compared with the priority dates in issue here. In Ranbaxy [2006] FCA 1787 , 71 IPR 46 , the priority date of the broader patent was 30 May 1986 and that of the enantiomer patent 21 July 1989. In the case of Alphapharm [2008] FCA 559 the Australian Citalopram Patent had a priority date of 14 January 1976 and the enantiomer patent 14 June 1988. The common general knowledge found by Lindgren J to relate to the enantiomer patent and by Young J to relate to the broader patent was very much in the same time band as that relevant to construction of the patent in suit here. Naturally, the field of each invention is somewhat different but the principles of stereochemistry as they were understood at the time should not have varied much. There is no suggestion of any crucial and widely known developments during the years in question. 133 Here, there is no suggestion that any of the process claims do not work in that sense and there is no suggestion that the compounds claimed do not usefully inhibit platelet aggregation. Indeed, it has not been contended that the compounds claimed are not better in that respect than the racemate. I do not see that the claims that the properties were "unexpected" or "surprising" have anything to do with that concept. The decision of Young J in Ranbaxy [2006] FCA 1787 , 71 IPR 46 must have been based upon the view that the specification there was construed as promising a particular level of result. The correctness of the decision on this point was left open in the Full Court ( Ranbaxy [2008] FCAFC 82 at [142] [144]).