Generic Form of Drug Plavix Enters Market

Sanofi-Aventis and Bristol-Myers Squibb Co. are facing generic competition in the U.S. for their top-selling Plavix blood-thinning pill five years earlier than planned.

Apotex Inc., a closely held Canadian maker of generic drugs, said it started shipping cheaper copies Tuesday. Plavix is the world’s second-best-selling pill. Sanofi and Bristol-Myers lost a bid Monday in U.S. court to block the sales.

At stake for Paris-based Sanofi and New York-based Bristol-Myers is $6.3 billion in annual revenue from the $4-a-day pill. A new generic drug may account for 90% of prescriptions within three months of introduction, according to IMS Health Inc., a Fairfield, Conn., provider of pharmaceutical data. Weston, Canada-based Apotex may be subject to penalties if the patent is later upheld in court.

“Sanofi and Bristol are showing their intent to resume aggressive legal action to protect their interests,” Chris Shibutani, a JPMorgan Securities Inc. analyst in New York, said in a note to clients. “We believe it is in all the parties’ interests to move quickly, and will look for prompt movement to a full trial. We expect that a settlement at this point is very unlikely.”

Shares of Bristol-Myers fell $1.56, or 7%, to $21.21. The stock has lost 18% since July 26, the day before the drug maker disclosed a Justice Department investigation of an accord to keep the Apotex product off the market until 2011.

Sanofi’s U.S. shares lost 41 cents, or 1%, to finish at $44.45. The shares have declined 11% since July 26.

Shares rose for Medco Health Solutions Inc., Caremark Rx Inc. and Express Scripts Inc., the three biggest companies that manage drug benefits for employers and health insurance providers. They would profit by substituting the Apotex product for Plavix because the markup on generic drugs is higher.

Plavix prevents the formation of blood clots by keeping platelets from clumping together. Doctors prescribe it to reduce complications in patients having heart attacks or those undergoing artery-clearing procedures, or to prevent heart attacks and strokes in people with an elevated risk.

“The companies are evaluating their legal and commercial options, as well as possible remedies under the agreement with Apotex,” Sanofi said in a statement. The partners “intend to vigorously pursue enforcement of their patent rights in Plavix.”

The drug is Bristol-Myers’ biggest product and Sanofi’s second-largest. Its sales last year were second only to those of Pfizer Inc.’s Lipitor cholesterol pill, with $12.2 billion. The companies spent $121.4 million advertising Plavix last year in the U.S., according to Nielsen Medial Research.

“This is going to be the biggest seller in the history of our company,” said Barry Sherman, 64, chief executive and principal owner of Apotex.

Apotex had agreed not to sell a generic version of Plavix until 2011 in return for payments of at least $40 million from Sanofi and Bristol-Myers. U.S. state attorneys general last month objected to the accord, which was intended to settle patent litigation.