The Associated Press

WASHINGTON (AP) - Three Democratic senators have asked the Federal Trade Commission to re-examine the 2007 merger of prescription drug giants Caremark and CVS, expressing concern the merged company will drive independent pharmacies out of business.

Sens. Byron Dorgan of North Dakota, Russell Feingold of Wisconsin and Any Klobuchar of Minnesota said they've been hearing from constituents that the pharmacies they rely on for medicine and advice are at a competitive disadvantage.

In a letter dated Tuesday, the senators said four large companies are now handling reimbursement of most prescription drug claims, covering some 240 million Americans.

"In some cases, patients who do not elect to fill prescriptions through Caremark's mail order business are charged higher copays," the letter said. "In other cases, beneficiaries are limited in the number of prescriptions they may fill at their local community pharmacy."

Carolyn Castel, vice president of corporate communications at CVS Caremark, responded that the merger is making pharmacy health care more accessible, effective and affordable.

Castel said the merged operations "provide greater choice and more convenience for customers and patients, improve health outcomes, and lower overall health care costs for plan sponsors and participants."

She added, "Any suggestions that our business practices are anticompetitive or that we are violating antitrust laws are totally false."