UPDATE 1-U.S. FDA approves higher dose of clot drug Plavix

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NEW YORK, Sept 27 (Reuters) - U.S. regulators have approved a higher-dosage tablet form of the blockbuster blood-clot preventer Plavix that will offer convenience to some patients arriving at hospitals with heart problems, the drug's makers said on Thursday.

Plavix, one of the world's best-selling medicines, is now typically taken in 75-milligram doses. It is used to prevent blood clots that can cause heart attacks and strokes, and works by preventing disc-shaped elements of the blood called platelets from sticking together.

"The 300-milligram tablet is bioequivalent to four 75-milligram . . . tablets of Plavix," Bristol-Myers Squibb Co (BMY.N) and Sanofi-Aventis (SASY.PA) said in a release.

The 300-milligram tablet will offer convenience as an initial "loading dose" for patients coming to hospitals with signs of small heart attacks or chest pains that can precede heart attacks, they said.

The companies said guidelines established by the American College of Cardiology and the American Heart Association recommend a 300-milligram initial dose of Plavix, taken along with aspirin, for such patients.

Despite the guidelines, the drugmakers said many patients entering hospitals with heart symptoms are not given the hefty recommended initial dose of Plavix.

Plavix is also widely used to prevent blood clots among patients who have received stents, tiny mesh-like devices used to prop open coronary arteries that have been cleared of plaque.

Shares of Bristol-Myers were little changed in morning trading on the New York Stock Exchange. (Reporting by Ransdell Pierson)