Actonel, also known in pharmaceutical circles as risedronate sodium tablets, is used to treat and prevent osteoporosis, mainly in postmenopausal women.

Aventis is objecting to an application by Teva to market in the United States a generic version of the treatment.

Last month Teva filed an application with the US Food and Drug Administration to win approval to market the product.

The FDA cannot approve marketing of Teva’s version of the drug for another 30 months, or until Teva receives a court ruling in its favour, because Aventis began legal action within 45 days of the application.

The Israeli company argues that its generic version would not infringe on the Actonel patents held in the US by Aventis and US group Procter and Gamble.

Sales of Actonel jumped by 70.6 percent in 2003 to EUR 769 million (USD 951.4 million), boosted by the introduction of a pill that can be taken once a week instead of daily.