Aventis received a second rejection from the United States Patent Office (USPTO) on Aventis' application for re-issuance of US Patent no. 5,389,618 ('618 patent), relating to Lovenox. Even though this rejection is characterized as a "final rejection" by the USPTO, Aventis has the option of continuing the re-issuance process or filing an appeal, the release said.

The company believes that if its arguments in response to this rejection are favourably received, the USPTO could issue a notice of approval on Aventis' application by the end of this year and finally reissue the patent in 2005.

Aventis filed an application with the USPTO in May 2003 seeking re-issuance of the '618 patent. A re-issuance application is typically used to seek modifications in the specifications of a granted patent. During the reissuance process, the '618 patent remains in force.

Aventis also previously announced in August of 2003 that it filed lawsuits to enforce the '618 patent (which expires on February 14, 2012) against Amphastar Pharmaceuticals, Inc. and Teva Pharmaceuticals USA who were seeking to market generic versions of Lovenox by filing Abbreviated New Drug Applications (ANDAs) with the US FDA.

By suing to enforce the '618 patent, Aventis initiated an automatic stay prohibiting the FDA from approving these ANDAs for 30 months, or until an earlier court decision adverse to Aventis in a patent infringement lawsuit. Aventis has agreed to be bound in the lawsuit by the ultimate non-appealable outcome of the re-issuance proceeding.

The leading low-molecular-weight heparin, Lovenox was approved in the United States and Canada in 1993. It has been available in Europe since 1987 and is known under the brand names Lovenox, Clexane and Klexane. Lovenox is the only low-molecular-weight heparin approved by the FDA for the indications-Prophylaxis of deep-vein thrombosis; for patients undergoing abdominal surgery who are at risk for thromboembolic complications; for patients undergoing hip replacement surgery, during and following hospitalization; for patients undergoing knee replacement surgery.

Also for Prophylaxis of ischemic complications of unstable angina and non-Q-wave myocardial infarction, when concurrently administered with aspirin etc, the release added.