The U.S. Food and Drug Administration has warned Sanofi-Aventis SA (SNY) that an advertisement for its drug, Uroxatral, fails to mention risks associated with the medicine.

The advertisement for Uroxatral, used to treat enlarged prostates, was a "tent card" and was presented with an outdated version of the drug's label, according to a letter the FDA sent to Sanofi on Friday. The letter was posted on the FDA's Web site Tuesday. Tent cards are folded and placed atop tables to display information on two sides.

The FDA approved Uroxatral in 2003 to treat patients with enlarged prostates. The label for the medicine has been revised seven times.

The tent card said "ALWAYS IN THE BATHROOM...especially at night?" and "Relief begins with U." The FDA said this statement misleadingly suggests Uroxatral can be used to treat anything that keeps a person in the bathroom, such as an overactive bladder.

The FDA said the back of the card did include risk information. The FDA said omitting risk information from the front of the card can't be corrected "merely by including the statement 'Please see Important Safety Information on back."

The FDA wants Sanofi to stop dissemination of the ad and to respond to the agency by Nov. 6.

-By Jared A. Favole, Dow Jones Newswires; 202.862.9207; jared.favole@dowjones.com