Bermuda-based pharmaceutical company Warner Chilcott is suing three rivals for infringing a patent on its antibiotic drug Doryx.

Warner said one its subsidiaries had filed lawsuits in the District Court for the District of New Jersey against Mutual Pharmaceutical Company Inc., Mylan Pharmaceuticals Inc. and Impax Laboratories Inc.

Warner markets and sells Doryx delayed-release tablets in 150, 100 and 75 mg strengths under a licence agreement with Mayne Pharma International Pty. Ltd., which is joining the Bermuda company in the litigation.

The lawsuits are in response to the submission of applications to the US Food and Drug Administration (FDA) by each of Mutual, Mylan and Impax requesting approval to manufacture and sell generic versions of Doryx 100 and 75 mg delayed-release tablets prior to the expiration of the patent in 2022.