Aug. 30 (Bloomberg) -- Sanofi-Aventis SA’s experimental anti-clotting drug prevented deaths and cardiac complications in people with mild heart attacks and severe chest pain better than standard treatment, a study found.

Patients given Sanofi’s otamixaban were 40 percent less likely to have a second heart attack, need an emergency procedure to open clogged arteries or die than those given heparin and Schering-Plough Corp.’s Integrilin. The study, from the second of three phases needed for approval, was presented at the European Society of Cardiology meeting in Barcelona today.

While heparin and Integrilin have been used for years to prevent clots that cause complications in patients undergoing procedures to clear clogged arteries, it’s difficult to get the right dose and patients must be closely monitored. If otamixaban proves effective in larger clinical trials, it may also compete against other blood thinners, including Sanofi’s Lovenox, the Medicines Co.’s Angiomax and GlaxoSmithKline Plc’s Arixtra.

“There is intense interest in finding a more effective, reliable and safe replacement for heparin,” said Marc Sabatine, the lead researcher and a cardiologist at Brigham and Women’s Hospital in Boston. “With otamixaban, we can use a weight-based dose and patients fall right into the target range. It’s much more convenient to give.”

Otamixaban is given intravenously and inhibits a key enzyme needed for blood to clot. A previous study found the drug was effective in lower-risk patients undergoing a planned procedure to clear the heart arteries. The new trial involved a higher risk group of patients undergoing the procedure known as angioplasty. Both trials were funded by Paris-based Sanofi.

$1 Billion Drug

If the drug proves safe and effective in larger studies, it could eventually generate $1 billion to $1.5 billion in annual sales, Alexandra Hauber, an analyst at J.P. Morgan, said in an Aug. 21 note to investors. The earliest it could be available is 2012, she said.

“Due to the limited disclosure provided by Sanofi in the agent, we believe that it is not yet on the radar screen of investors,” she said, describing the study as a potential “upside surprise” for the company.

The lowest two doses of the drug were insufficient to keep the arteries clear in the study, while the highest level raised bleeding rates, Sabatine said in a telephone interview. While the main goal was to find the best dose for larger trials, the heart risks after a week were significantly lower in patients getting a moderate dose of otamixaban, without increasing the risks of serious bleeding, he said.

Intermediate Dose

Patients getting the intermediate dose also had a 46 percent reduction in death and heart attack rates, and the benefit lasted through the full six months of the study.

“We achieved our goal of figuring out what is the right dose range for a big, phase 3 trial to definitively establish the drug’s benefit,” he said. “This may not only replace heparin, it could simplify treatment.”

Planning for the final, phase 3 studies has started, and it may take two to three years to get results, Sabatine said.

In an accompanying comment in The Lancet, John Eikelboom and Jeffrey Weitz of McMaster University in Canada said otamixaban needs to show that it’s better than heparin and Angiomax, or bivalirudin, before doctors would prescribe it.

“Otamixaban might be a useful alternative to heparin for patients with acute coronary syndromes” undergoing angioplasty, they wrote. “However, do we need another parenteral agent for this indication? Without safety or convenience advantages, otamixaban would need to show efficacy that is superior not only to heparin but also to bivalirudin, before it would be adopted for clinical use.”

To contact the reporter on this story: Michelle Fay Cortez in London at mcortez@bloomberg.net

Last Updated: August 30, 2009 04:32 EDT