Final word

Vicki Salmon, Associate at biosciences law specialists Eversheds LLP, on the ramifications of the Lipitor patent dispute.

Indian generic pharmaceutical company Ranbaxy recently launched attacks around the globe on Pfizer’s patents for its anti-cholesterol drug, Lipitor. Lipitor is one of the world’s blockbuster drugs, with some putting the market in the region of US$12 billion annually. If Ranbaxy succeeds, then it would be able to launch its generic version, coming into the market while the price was still high and before it dropped to typically 80-90 percent of its post-patent price.

Lipitor is the brand name for atorvastatin, which was invented by Warner-Lambert and then acquired by Pfizer. Patents were sought and obtained in many countries for the main active ingredient, with further patents obtained for follow-up developments. Ranbaxy attacked not only the master atorvastatin patent, but also subsidiary patents on the calcium salt.

Although most of the world’s judgments have been in Pfizer’s favor, Ranbaxy has vowed to fight on through the appeal process. Given that each country has a different system for filing and obtaining patents – and also its own standards as to what can be patented, how patent claims should be interpreted, what amounts to infringement and how patents can be attacked – the degree of unanimity between the different courts is interesting and reassuring.

The US case

Pfizer’s US patents are not due to expire until 2010 and 2011. The original term was extended from 2006, on the grant of the marketing authorisation. Ranbaxy applied for an abbreviated new drug application (a request to the FDA for commercial approval based on the approval already given – for example, to the patented medicine) to sell the generic version and was sued by Pfizer for patent infringement. Ranbaxy tried to show that the patents were not enforceable; in the US, it sought to rely on the doctrine of inequitable conduct, claiming that Pfizer had withheld information from the US Patent and Trademark Office when obtaining the patent protection. It also argued that the patents were unenforceable on the grounds of anticipation, obviousness and/or double patenting. These failed and Pfizer’s US monopoly continues.

The UK case

Pfizer’s UK patents will also expire in 2011 and 2010. In this case, Ranbaxy asked the court to state that it did not infringe one of Pfizer’s patents and that the other patent was invalid. Unlike the US position, where there is a presumption that a granted patent is valid, there is no such presumption in the UK. The court will look at whether the invention was patentable; this includes whether it was new and not obvious.

Ranbaxy tried to argue that it did not infringe the claims of the master UK patent because they only covered the racemic mixture for the enantiomers of atorvastatin. Ranbaxy said that it should therefore be free to sell a pharmaceutical composition, which only contained one of them. The English court did not agree with this argument and held that the patent claims covered both the racemic mixture and the individual enantiomers.

Ranbaxy then sought to revoke the subsidiary patent, which covered the calcium salt of atorvastatin. This was argued both over the disclosure in Pfizer’s master patent and also over the disclosure in a third Pfizer patent application that related to atorvastatin. This third application was filed after the master patent, but before the subsidiary patent.

In Europe, the patent law provides that where an earlier patent application for the same subject matter has been filed, then it can be used to assess the novelty of a later patent application, even when the earlier application has not been published by the time the later patent application was filed. This applies whether the earlier unpublished patent application is filed by the same inventors or by unrelated inventors. There is no grace period and the chance of self-collision exists. The purpose is to stop the same invention from being patented twice. However, in practice, as long as one can make a difference between the two documents, however slight, the second patent can be granted. The analysis is strictly on novelty and not on how obvious it would be to adapt the earlier invention.

Ranbaxy relied on this to invalidate the subsidiary patent for the calcium salt. They also successfully relied on the fact that this would be an obvious modification of the master patent. Pfizer, predictably, are appealing.

Other jurisdictions

Proceedings have also been taking place on the same patents in at least Norway, Austria and Ireland. The Norwegian courts upheld Pfizer’s patents, but in Austria one patent was overturned.

The devil is in the details

One of the difficulties and expenses of patent law is that each country has its own system, which means that a patent has to be obtained in each country of interest and then enforced or revoked in that country. Although there are significant similarities as to what is required to obtain a patent, the devil is always in the detail, and the laws will differ as to how one meets the tests of novelty or inventive step, or what one has to disclose in the application. This makes advising in a multi-jurisdictional case interesting and challenging. And yet, it is reassuring to see that there does seem to agreement in the outcomes from the different courts, notwithstanding the differences in approach.

This is good news for Pfizer. It can maintain its premium price for Lipitor, which in turn means that its share price is more secure and it has profits for investing in further research. However, Ranbaxy have not given up yet and we shall have to see whether it succeeds better in round two, on appeal.