Patent

Pfizer’s Pregabalin – An IP Tale of Pain and Second Medical Use patents, Part I


(Image Source: https://commons.wikimedia.org/wiki/File:Lyrica.jpg)

(Image Source: https://commons.wikimedia.org/wiki/File:Lyrica.jpg)

In a fascinating development, the England-Wales Patent court last month pronounced the judgment on Pfizer Group’s Warner-Lambert Company’s dispute regarding its Lyrica medicines, containing the compound pregabalin. This case touches on issues including Second Medical Use patents and ‘skinny labels’ and threats to sue, so read on for a riveting IP story! [Long post ahead!]

Background

Given the complex background, a bit of backstory is quite necessary here. Until recently Warner-Lambert (which is part of the Pfizer Group) held the patent over pregabalin for epilepsy, generalised anxiety disorder and neuropathic pain. Soon after obtaining the original patent, Pfizer had obtained a Second Medical Use patent over pregabalin for the treatment of neuropathic pain.

Now, ‘second medical use’ patents are considered to be infringed only if a generic pharmaceutical company markets the specific compound for the specific ‘use’ covered under ‘second medical use’. In the current case, infringement includes a requirement to do so intentionally. This requirement may be limited to cases such as the present one where the Swiss form is used, as it gives a mental element to the claims through legal fiction.

The problem for Pfizer here is that while a generic company may only market its product for the permitted indications, referred to as a ‘skinny label’, that doesn’t necessarily mean that their products do not end up being used as painkiller. This happens because doctors simply write a prescription for pregabalin, with the compound name only, and without any indication of the condition for which it is prescribed. The pharmacist then supplies the consumer with generic versions of the same, with no indication of what purpose it was assigned for. Pfizer argued that this caused losses to it and infringed its patent, as medicines other than its own ‘Lyrica’ would be used as painkillers. This was particularly problematic for it in the UK as the United Kingdom’s National Health Service (‘NHS’) doctors usually prescribe drugs simply by the drug’s generic name. (The situation, in my experience, differs in India, with doctors prescribing by generic or brand names interchangeably, though if our readers are aware of any differences in this, please do comment!).

In this sort of an infringement, the generic manufacturer itself may or may not actually press for the usage of its product as a painkiller, and the infringement of Warren-Lambert’s patent may actually end up occurring by no direct fault but simply as a consequence of an unclear system. At the same time, Pfizer complained that Actavis’ use of certain modified ‘blue box’ wording on their packaging was intended to promote the use of their drug for treating pain (¶ 445).

In order to settle this issue, Pfizer went to court. Four times. So the decision I am discussing here is actually the fifth Court judgment on this matter, with other litigations still pending. To complicate issues further, pursuant to its fourth round in Court (‘Warner-Lambert IV’), Pfizer obtained an order for the doctors of NHS to prescribe Lyrica, by the brand name, for pain, which angered a substantial number of people (¶ 5).

It must be noted, as the judgment itself does, that this was an unprecedented situation in the UK (¶ 419).     Second Medical Use Patents themselves are a nascent field of law. The idea behind such a patent is to incentivise finding new uses for existing medicines, as that saves a substantial amount of testing costs, and medicines have been known to have multiple applications. Since even such development requires substantial research, Second Medical Use patents are allowed in order to permit the researcher to recoup his research costs.

The Current Judgment

There are three arms to the Pfizer judgment. The first is the question of the validity of the patents, the second is the question of infringement itself assuming the validity of the patents, and the third is the ‘threatening’ nature of certain letters sent by Pfizer to multiple recipients regarding the use of generic pregabalin as a painkiller.

Validity

On the question of the validity of Pfizer’s patents, the Court here found Pfizer’s patent claims for pregabalin as a painkiller itself to be invalid, except in certain specific kinds of pain. As I had mentioned earlier, the only ‘unique’ use that was left in Pfizer’s patent was the treatment of neuropathic pain. The patent claim, however, was broadly oriented, and covered multiple types of pain other than the neuropathic kind, including inflammatory pain, cancer pain, idiopathic pain (i.e., pain of unknown origin), and so on. Of the 14 categories of pain that the patent claimed pregabalin could be used to treat, six claims relating to the use of pregabalin for neuropathic pain were invalidated by Justice Arnold on the grounds that they were ‘insufficient’ in terms of description (¶ 339-358). Crucially, the two claims which Pfizer was using as a basis for its infringement claim were included in the six invalidated claims. (It must be noted here that the invalidation of the patent only applies in the UK.)

As a side note, Justice Arnold also found that the ‘common knowledge’ test for ascertaining the validity does have a territorial dimension; i.e., in this case the ‘common knowledge’ should have been the UK, with certain caveats (¶ 123-124 in the judgment). This is particularly relevant since Justice Arnold goes on to find that while the use of gabagablin, the precursor of pregabalin, as an analgesic for neuropathy-related diseases was common knowledge in the US, the evidence regarding this being common knowledge in the UK was insufficient.

Threats

On the question of the threatening letters, the Court found a majority of the communications sent out by Pfizer to be of a threatening nature, and held Pfizer liable for “making groundless threats of patent infringement proceedings”. These emails were part of communications Pfizer sent out before it obtained the NHS Order, telling doctors and pharmacists and their associations that they were infringing its alleged patents by giving out non-Lyrica pregabalin through the process described above. These letters were of a nature which suggested that the persons they were sent to would find themselves at the wrong end of a patent suit if they did not stop their activities.

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