Dec. 7 (Bloomberg) -- Sanofi-Aventis SA, France's Largest drugmaker, sued generic-medicine company Apotex Inc. over Uroxatral, a drug used for treating prostate-gland enlargement.

Sanofi claims Apotex infringed the so-called U.S. '491 patent by trying to market a generic version of the medicine, according to a complaint filed yesterday in federal court in Wilmington, Delaware. Apotex, the largest Canadian-owned pharmaceutical company, has asked U.S. regulators for permission to sell a generic version of Uroxatral, the complaint claims.

``Defendants were aware of the existence of the '491 patent at the time of the submission,'' Sanofi said in its complaint.

Sanofi, based in Paris, had $35.6 billion in sales last year. The company has been seeking products to help revive profits as its older drugs face generic competition. The '491 patent was issued in 1987.

The drug, whose chemical name is alfuzosin hydrochloride, is approved for sale by the U.S. Food and Drug Administration, according to the complaint. Prostate enlargement usually occurs in men over 40, and about half of all men in their 60s have some related symptoms, according to Sanofi's Web site.

Apotex spokesman Elie Betito didn't immediately return a call seeking comment. Closely held Apotex is based in Weston, Ontario.

Sanofi-Aventis rose 68 cents to 65.7 euros in Paris trading today. The stock has fallen six percent this year.

To review the disputed patent through the U.S. Patent and Trademark Office's Web site, search for patent number 4,661,491 at http://patft.uspto.gov.

The case is: Sanofi-Aventis v. Apotex Inc. et al, 07-00792; U.S. District Court for the District of Delaware (Wilmington).

To contact the reporter on this story: Steven Church in Wilmington, Delaware, at schurch@bloomberg.net.

Last Updated: December 7, 2007 11:13 EST