Barr Labs confirms patent challenge of Amrix extended-release capsules

Barr Pharmaceuticals, Inc. has confirmed that its subsidiary, Barr Laboratories, Inc., has initiated a challenge of the patent listed by Anesta in connection with its Amrix (cyclobenzaprine hydrochloride) extended-release capsules, 15mg and 30mg.

Barr filed its Abbreviated New Drug Application (ANDA) containing a paragraph IV certification for a generic version of Amrix with the U.S. Food & Drug Administration (FDA), and following receipt of the notice from the FDA that Barr's ANDA had been accepted for filing, Barr notified the New Drug Application (NDA) holder and patent owner.

On November 26, 2008, Eurand, Inc., Cephalon, Inc., and Anesta AG filed suit in the U.S. District Court for the District of Delaware to prevent Barr from proceeding with the commercialization of its product. This action formally initiates the patent challenge process under the Hatch-Waxman Act.

Amrix (cyclobenzaprine hydrochloride) extended-release capsules, 15mg and 30mg had annual sales of approximately $53 million in the U.S., based on IMS sales data ending September 2008.