July 8 (Bloomberg) -- Sanofi-Aventis SA, France's largest drugmaker, said taking its Lovenox blood thinner for five weeks prevents more clots than using the medicine for the standard 10 days of treatment.

Acutely ill patients at risk of deadly clots lowered their chances of developing deep-vein thrombosis or pulmonary embolisms by 44 percent when given a five-week course of the injected drug compared with patients given the standard care, according to the results of a study presented at the International Society on Thrombosis and Haemostasis in Geneva today.

``Patients do not leave their risk for venous thromboembolism at the door when they leave the hospital,'' said Victor F. Tapson, a professor of medicine at Duke University Medical Center in Durham, North Carolina, in a statement.

Typically, severely ill and bedridden patients, whose reduced mobility puts them at risk of developing clots, are given Lovenox for 10 days as a preventive measure.

Sanofi is trying to expand the use of Lovenox, its best- selling drug with 2.4 billion euros ($3.3 billion) in revenue last year, as it struggles to get new medicines on the market.

The company faces patent challenges to Lovenox and has lost patent protection for the sleep drug Ambien. Last month, it withdrew its application for U.S. Food and Drug Administration approval for the anti-obesity drug Acomplia after an expert panel voted against recommending it.

To contact the reporter on this story: Angela Cullen in Frankfurt at acullen8@bloomberg.net.

Last Updated: July 8, 2007 04:14 EDT