Aventis has initiated patent infringement litigation against Teva Pharmaceuticals USA in response to Teva's application to market a generic version of Actonel (risedronate sodium tablets) in the US.

Aventis learned in July 2004 that Teva had filed an Abbreviated New Drug Application (ANDA) with the US Food and Drug Administration (FDA) that included Paragraph IV certifications against several patents for Actonel. Under US law, because patent infringement litigation was initiated within 45 days after receipt of the certification notice, the FDA may not approve marketing of Teva's proposed generic product until 30 months have elapsed, or until a court decision favourable to Teva is rendered in the litigation, whichever occurs first, release from Aventis said.

Risedronate sodium is a bisphosphonate that is currently approved in 82 countries worldwide. Risedronate 35 mg Once a Week and risedronate 5 mg daily are indicated for the treatment of osteoporosis in postmenopausal women. Risedronate 5 mg also is indicated for the prevention of osteoporosis in postmenopausal women and the management of glucocorticoid-induced osteoporosis (GIO).