BOSTON — Pharmacy benefits manager Express Scripts has agreed to pay $9.5 million in an agreement with 28 states over switching patients’ cholesterol drug brands, supposedly to control costs.

St. Louis-based Express Scripts Inc. will pay $9.3 million of the total to the states and the District of Columbia, to settle litigation by attorneys general alleging Express violated consumer protection laws.

Lynn Solomon is a spokeswoman for Montana Attorney General Mike McGrath. She said Thursday that Montana will receive $165,000 from the settlement.

The agreement includes another $200,000, to cover payments of no more than $25 each to individual patients. The payments will help defray the cost of physician visits and tests, linked to switches between rival brands of cholesterol-controlling drugs known as statins.

The agreement resolving a four-year investigation of St. Louis-based Express Scripts follows a similar $38.5 million multistate settlement in February with a rival benefits manager, Caremark, and a 2004 drug-switching settlement with Franklin Lakes, N.J.-based Medco Health Solutions Inc.

Through the agreements, state attorneys general “have changed how these companies treat patients and doctors when they ask to change their prescription medications,” said Martha Coakley, attorney general in Massachusetts, one of the participating states, with $255,000 in settlement money. “Those requests now include full information on costs savings and the reasons for the proposed switch.”

In addition to Montana, Massachusetts, Ohio and Washington, D.C., the participants in the settlement are: Arizona, Arkansas, California, Connecticut, Delaware, Florida, Illinois, Iowa, Louisiana, Maryland, Michigan, Mississippi, Missouri, Nevada, New Mexico, North Carolina, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, and Washington.

The same states were involved in February’s settlement with Caremark’s parent company, Woonsocket, R.I.-based CVS Caremark Corp.