Indianapolis-based Eli Lilly and Co. and London-based AstraZeneca Plc aren't expected to have an easier time gaining more of the market for blood thinners dominated by Bristol-Myers Squibb Co.’s Plavix after the drug loses U.S. patent protection Thursday.

Lilly’s Effient and AstraZeneca’s Brilinta will be used mostly by new patients who are beginning therapy, said Barbara Ryan, an analyst with Deutsche Bank who has a buy rating on New York-based Bristol-Myers’s stock. Plavix, and now the copycat pills that will hit the market, are still expected to dominate.

“Managed care has made it more difficult in general for the adoption of new products,” Ryan said. “Plavix has been around a while. It’s very effective, it’s a safe drug. Effient and Brilinta are really competing for new patient starts.”

More than 50 million people in the United States have taken Plavix since it was approved by regulators in 1997, according to Christina Trank, a Bristol-Myers spokeswoman. Now, though, the company is winding down promotion of the pill, and stopped advertising it last year.

Bristol-Myers said it will still push to have patients keep taking the brand, and is offering a “Plavix Choice Program” card that will let them get the medicine for $37 a month.

None of the newer blood thinners are expected to match the $7.09 billion Plavix sold in 2011, according to Seamus Fernandez, an analyst with Leerink Swann & Co. who follows all three companies. Sanofi, based in Paris, reported $2.76 billion in revenue last year from Plavix, which it co-promotes with Bristol-Myers.

Fernandez estimates Effient sales will peak in 2017 at $865 million, an increase from $303 million last year. Brilinta may reach $1.77 billion by then.

Bristol-Myers has said it’s well prepared for the loss of the drug, pointing to the company’s “string of pearls” strategy to refill its pipeline with small and mid-size deals. The drugmaker is interested in buying San Diego-based Amylin Pharmaceuticals Inc. and its diabetes drugs Bydureon and Byetta, which generated more than $650 million in revenue last year, Bloomberg reported on May 15.

Lilly shares were down 6 cents Thursday morning, to $40.69 each.