Delaware court rules on claim construction in Banzel patent row

A US district court yesterday (March 17) gave its opinion on how a group of disputed patent claims must be construed in a patent infringement case between Eisai and Novartis and several generic drug makers.

Eisai and Novartis sued Glenmark Pharmaceuticals, Hetero Labs, Lupin, Mylan and Roxane in five different actions in July 2013. The actions were consolidated in April last year.

They alleged the companies had infringed three patents covering antiepileptic drug Banzel (rufinamide). The generic makers had filed Abbreviated New Drug Applications with the US Food and Drug Administration to make and sell generic versions of Banzel, which is known as Inovelon outside the US.

Banzel is used to treat seizures associated with Lennox-Gastaut syndrome, a type of epilepsy. Last year, it generated US sales of $60 million.

The three patents—8,076,362; 7,750,028; and 6,740,669—cover Banzel’s active ingredient and its use as a pharmaceutical product. They are due to expire in 2018, 2019 and 2023 (including paediatric exclusivity) respectively.

Novartis owns the patents and exclusively licenses them to Eisai in the US.

However, the parties disagreed on how the terms in the patents’ claim construction should be construed.

Rufinamide is a crystal modification (crystal modification A) of a certain compound, and “crystal modification A” was among the disputed terms in the claim construction. The defendants offered four different proposals for how the term should be construed, each of which differed from that of Eisai and Novartis.

Yesterday, the court gave its own construction of nine disputed terms in the claims. It concluded that “crystal modification A” means: “A crystal modification of the compound 1-(2,6-difluorobenzyl)-lH-1,2,3-triazole-4-carboxamide, referenced as ‘A’, and having the characteristics specifically set forth in each respective claim or the claim from which it depends.”

Other disputed terms considered by the court were “sodium carboxymethylcellulose”, which it decided should be given its “plain and ordinary meaning”, and “in essentially pure form”, which the court defined as having a purity of more than 95%.

The case of patent infringement is still pending.