Nov 20 (Reuters) - Texas Attorney General Ken Paxton

sued Bristol Myers Squibb ( BMY ) and Sanofi, accusing

the drugmakers of failing to disclose that Plavix, which is used

to prevent blood clots, does not work effectively for many

patients.

Paxton said on Thursday the lack of disclosure caused

patients to be prescribed a "substantially inadequate or

inappropriate" medication, violating the Texas Health Care

Program Fraud Prevention Act.