Enforcing Second Medical Use Claims

The concept of second medical use claims in patents has always struck me as a bit odd, although this is probably partly due to the fact that I do not have a technical background in chemistry and try to avoid such patents at all costs. Those with a chemistry background probably find the concept of computer program claims equally odd. I know enough, however, to see that enforcing second medical use patents will tend to be a bit tricky, especially with the public policy argument about not preventing medical practitioners from doing what they want to do. This public policy is in place quite explicitly in the case of methods of medical treatment, where there are specific exceptions to patentability under Article 53(c) EPC. The same provision, however, also states that this does not apply to products, in particular substances or compositions, for use in any of these methods.

What this means in practice is that a patent can be validly obtained for a new use of a known pharmaceutical substance, provided this new use is not obvious. This is clearly beneficial for pharmaceutical companies, where new developments often occur through unexpected side effects (the unexpected effect of sildenafil citrate during trials for treatment of angina being perhaps the best known example). Enforcing such patents, however, can be more difficult, especially if the substance is already in use and prescribed for an existing condition. Although it might be possible to bring proceedings against another company under section 60(2) of the UK Patents Act for selling or offering to sell a product clearly indicated as being for the new patented use, is it also possible to go after doctors who prescribe an existing generic drug for the new patented use? 

This is apparently what Pfizer are trying to do. In a letter addressed to Clinical Commissioning Groups in the UK (released by Boing Boing here, and further commented on here in the WSJ), Pfizer indicate that their patent EP0934061 on the use of pregabalin for treatment of pain "may be infringed, even potentially unwittingly, by pharmacists and others in the supply chain, if they supply generic pregabalin for the pain indication. Without information, guidance and practical solutions from the authorities, Pfizer believes that multiple stakeholders, possibly without realizing, may contribute to patent infringement which would be an unlawful act". This has, predictably, resulted in expressions of outrage from Cory Doctorow and Ben Goldacre, the former being very much against patents and the latter is very much against big pharma in general. 

Claim 1 of the patent, as recently limited, reads:

Use of (S)-3-(aminomethyl)-5-methylhexanoic acid or a pharmaceutically acceptable salt therof for the preparation of a pharmaceutical composition for treating pain. 

The scope of this claim would appear to be sufficient to cover at least manufacturers and suppliers of pregabalin, provided there was a clear indication of using the substance for the treatment of pain. Including instructions to this effect together with the product would presumably be enough. The patent could not, however, cover the sale of pregabalin where there was no indication that it could be used for treating pain.

The question I have arising from this is what legal ground Pfizer has to pursue CCGs for infringement. They could presumably not pursue individual doctors or pharmacists for infringement, since section 60(5)(c) states that "An act which, apart from this subsection, would constitute an infringement of a patent for an invention shall not do so if [..] it consists of the extemporaneous preparation in a pharmacy of a medicine for an individual in accordance with a prescription given by a registered medical or dental practitioner or consists of dealing with a medicine so prepared", but are CCGs any different? It looks to me as though they may be on fairly shaky ground, and making veiled threats to CCGs is perhaps not a great idea. I am, however, not an expert in this area. Any comments would be welcome.

UPDATE 22/1/15: Thanks to a comment from IPKat Darren, a decision from the Patents Court relating to this matter has been brought to my attention. Darren has now commented on this here.