TULSA, Oklahoma - Walgreens announced Thursday it has entered into an agreement to purchase regional drugstore chain USA Drug.

The chain includes May's Drug, Med-X and Drug Warehouse stores located in several states including Oklahoma.

A Walgreens news release says the transaction includes all 144 of the chain's stores for a total of approximately $438 million.

USA Drug recorded sales of $825 million in 2011.

"This acquisition expands our business in an important region of the country," said Walgreens President and CEO Greg Wasson. "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 transaction is subject to regulatory requirements and other closing conditions, and is expected to close around September 1, 2012.

Walgreens says the acquired drugstores will continue in the near term to operate under their current brand names after the transaction closes, and decisions will be made over time regarding the best, most effective way to harmonize Walgreens and the acquired brands.