Walgreen Company, the parent of the Walgreens drugstore chain, says it will no longer participate in any new or renewed prescription drug plans managed by the CVS Caremark pharmacy benefit manager.

Walgreens, Deerfield, Ill., has concluded that the partnership is no longer in the best interest of its customers, pharmacists, and shareholders, the company says. Walgreens will continue to participate in CVS Caremark plans that are already in place.

Walgreens says it gets too little information when CVS Caremark, a unit of CVS Corp., Woonsocket, R.I., transfers a plan from one CVS pharmacy network to another, differently priced network.

The overall unpredictability of reimbursement rates also contributed to the decision, Walgreens says.

“We have come to feel that CVS Caremark’s pharmacy benefit management practices are inconsistent with the value we provide as the largest pharmacy provider in its network,” says Kermit Crawford, Walgreens executive vice president of pharmacy.

Walgreens has about 7,500 drug stores in the United States.