DEERFIELD, Ill. — Walgreen Co. made a pair of purchases earlier this month, adding 18 drug stores to its network and swapping its long-term care operation for a bigger stake in the home infusion business.

The new stores, in five Midwestern and Western states, are former ApothecaryRx LLC units that Walgreens acquired from Graymark Healthcare Inc. The $35 million deal for the stores is expected to close later this year.

Just over a day after it made that deal, Walgreens announced an agreement with Omnicare Inc. in which Walgreens will acquire Omnicare’s home infusion operations in six states, and Omnicare will acquire Walgreens’ long-term care pharmacy unit. In addition, Walgreens will take over Omnicare’s compounding pharmacy in Nevada and its home care management business in Maryland.

In exchange, Omnicare will get Walgreens’ long-term care operations in Colorado, Texas, Florida, Georgia and Maryland.

“By divesting our long-term care pharmacy business, we are able to have a stronger focus on our overall growth strategy while taking advantage of a specific opportunity to grow our infusion services,” Walgreens president and chief executive officer Greg Wasson says. “Acquiring Omnicare’s infusion business allows us to expand into currently underserved markets, while also strengthening our position in existing markets.”

The deal solidifies Walgreens’ position as the nation’s largest provider of home infusion services, he says.

The ApothecaryRx stores acquired by Walgreens are located in Colorado, Oklahoma, Minnesota, Missouri and Illinois and will fortify the chain’s already extensive network in those states.

Currently, Walgreens has 155 stores in Colorado, 100 in Oklahoma, 139 in Minnesota, 194 in Missouri and 564 in Illinois.

Such hallmarks of Walgreens’ operations as 24-hour and drive-through pharmacies; automatic prescription refill service; prescription text messaging alerts that notify customers when their prescriptions are ready for pickup; prescription labels in 14 languages; prescription records available at any Walgreens nationwide; and Walgreens Prescription Savings Club are expected to be added to the new stores.

The acquisition of the 18 stores is the latest takeover move by a company that until recently had shied away from using acquisitions to expand its store base. In just the past few years, Walgreens has purchased several midsize chains and has expanded its presence to all 50 states and Puerto Rico.