NEW YORK — John Spina, vice president of retail integration and new format development at Walgreen Co., will continue to oversee the company’s integration of Duane Reade Inc.

Spina, who has led the process since the acquisition was announced in February, will work closely with Duane Reade chairman and chief executive officer John Lederer, who will continue to direct the drug store chain’s operations, according to Walgreens.

Spina’s responsibility for leading Walgreens’ Rewiring for Growth efficiency initiative –— which is on track to deliver $1 billion in annual cost reductions in fiscal 2011 — was recently shifted to Don Huonker, Walgreens’ senior vice president of health care innovation.

Walgreens’ acquisition of Duane Reade, including 258 stores as well as the regional chain’s corporate office and two distribution centers, closed early this month.

Walgreens currently plans for the stores to continue operating under the Duane Reade banner. With 70 Walgreens stores in metropolitan New York City, Walgreens says it will consider the most effective way to harmonize both brands over time.

“Just as Walgreens has been a trusted community pharmacy for more than 100 years, we plan for Duane Reade to continue as the leading drug store that millions of New Yorkers rely upon,” says Walgreens president and CEO Greg Wasson. “By combining the strengths of our two companies, we can improve our position as the most convenient provider of consumer goods and services, and pharmacy, health and wellness services in the country.”

Walgreens says it intends to promptly repay or redeem all outstanding debts of Duane Reade and its affiliates.