Cheaper generic versions of blood thinner Plavix, the world's second-best-selling medicine, have just been approved for sale.

The Food and Drug Administration says it's given seven companies permission to sell generic Plavix, or clopidogrel (kloh-pidd-OH'grell), in the standard 75 milligram dose. The agency has given four companies an OK to sell the pills in the 300 milligram dose.

Plavix is taken every day by millions of people to prevent heart attacks and strokes.

The drug's patent just expired in the U.S. and has expired in several European countries and other major markets in the last year or so.

Brand-name Plavix is marketed jointly by Bristol-Myers Squibb Co. and Sanofi SA. They're now offering coupons giving a big discount off the brand.