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8 January 2018Americas

Federal Circuit hands win to Apotex in tablet coating case

The US Court of Appeals for the Federal Circuit has handed Apotex a win in a dispute over a tablet coating.

In a non-precedential ruling released on Thursday, January 4, the Federal Circuit found that the US District Court for the District of Delaware had erred in its claim construction and finding that Apotex infringed two patents.

The patents, US numbers 7,790,199 and 7,829,121, are owned by Aptalis Pharmatech and Ivax International and relate to extended release dosage forms of cyclobenzaprine hydrochloride, a skeletal muscle relaxant.

Extended release formulations can sustain “therapeutically effective drug concentrations over a prolonged period by releasing the drug at a slower rate”.

Both of the patents teach two different extended release formulations that use a water insoluble polymer coating, referred to as membrane systems and matrix systems.

The dispute began when Apotex filed an Abbreviated New Drug Application (ANDA) to manufacture and sell a generic version of Amrix (cyclobenzaprine), which is currently sold by Teva. Aptalis then sued Apotex for infringement.

Apotex responded by claiming that it does not infringe because its products contain a matrix-style formulation, not a membrane system.

In a matrix-style formulation, a water insoluble polymer is mixed together with the drug and compacted into a tablet, while in a membrane system, a water insoluble polymer coating is applied onto an active-containing core.

At the centre of the dispute is the construction of “an extended release coating comprising a water insoluble polymer membrane surrounding said core.

Before the district court issued its claim construction order, the parties agreed that “a water insoluble polymer membrane surrounding said core” means “a water insoluble polymer covering that surrounds the active core”.

The district court then construed “extended release coating” as a “layer of any substance that is applied onto the surface of another, the purpose of which is to delay the release of a drug in order to maintain the drug at therapeutically effective concentrations over an extended period of time”.

On this construction, the court found that Apotex’s ANDA product contained an extended release coating and infringed the asserted claims.

But the Federal Circuit came to a different conclusion and vacated the infringement finding.

“We conclude that the district court erred by not construing the term ‘extended release coating’ to require a continuous outer film, as taught by the intrinsic evidence,” noted Circuit Judge Kara Stoll, on behalf of the Federal Circuit.

Stoll added that prosecution history offers additional support for construing “extended release coating” to require a continuous outer film.

The district court’s infringement finding was vacated and remanded for further proceedings consistent with the Federal Circuit’s claim construction.

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