DEERFIELD, Ill. — As it continues to increase its presence across the country, Walgreen Co. has purchased USA Drug.

As it continues to increase its presence across the country, Walgreen Co. has purchased USA Drug.

The $438 million acquisition adds 144 outlets in seven states in the Mid-South and Great Plains to Walgreens’ store base.

"This acquisition expands our business in an important region of the country," Walgreens president and chief executive officer Greg Wasson said when the deal was announced. "It will provide significant new pharmacy business for us in this region while also enabling us to bring the Walgreens experience to many additional smaller communities where USA Drug has developed strong operational expertise."

The deal marks the second time in two years that Walgreens has taken over stores operated by USA Drug. In 2010 Walgreens bought the pharmacy files of 17 of USA’s Super D and Ike’s units in Memphis and purchased two Ike’s stores outright.

In recent years USA Drug, which operates stores under five different banners and does an estimated $825 million a year in sales, has focused on enhancing established stores.

Executives at the Little Rock, Ark.-based chain say they agreed to sell the company to Walgreens because they felt the nation’s largest drug chain shared many of the same values as they did and would continue to provide USA Drug’s customers with the same level of service the company has offered since its inception in 1968.

"We chose to sell to Walgreens not only because it is the premier drug store company in our industry, but also because Walgreens will continue to provide our customers with the service and products they have come to expect," USA Drug owner and chairman Stephen LaFrance says.

Walgreens says it will continue to operate the acquired stores under their current names, with decisions made over time regarding the best, most effective way to harmonize Walgreens and the acquired banners.

Walgreens says the deal will not have a material impact on earnings per share in fiscal 2012 and is expected to be finalized by early September.