Credit: NPG

Pfizer has successfully fended off a patent challenge by a group of generics companies that wanted to market their own version of Lyrica (pregabalin). The drug, which is used to treat seizures and pain, had a revenue of US$525 million in the United States in the fourth quarter of 2013.

The collective of generics companies — which included Teva, Lupin, Actavis and Cobalt — challenged a key claim in one of Lyrica's patents (US 6197819) that described 4-amino-3-(2-methylpropyl) butanoic acid. Of note, Lyrica is the (S)-enantiomer of this compound. The generics challengers asserted that this claim covered only the racemate, not the (S)-enantiomer. In this way, their proposed products, which would contain “non-racemic mixtures”, would not infringe on the patent.

But Pfizer said that the compound described in the claim was not limited to the racemate, so it could be any isomeric form.

The US Appeals Court noted that, elsewhere in the patent, Pfizer had used specific terminology ((R), (S), racemic and so on) to specify when it referred to a specific isomeric form. In the Court's opinion, there was no basis to support the assertion of the generics companies that the absence of an (R) or (S) prefix in the claim meant that it referred to the racemate.

So because the key claim encompassed the compound in any enantiomeric form, the products proposed by the generics companies would have infringed on Lyrica's patent.

The Court also found, in Pfizer's favour, that Lyrica was sufficiently described in patents to enable others to make it, and that Lyrica was not obvious over other compounds with a similar structure and anticonvulsant activity that were described in the prior art. The '819 patent expires in December 2018.

Pfizer versus Teva et al.: http://www.cafc.uscourts.gov/images/stories/opinions-orders/12-1576.Opinion.2-3-2014.1.PDF