Willkie Farr & Gallagher and Paul Weiss Rifkind Wharton & Garrison have taken lead roles on the $2.6bn (£1.6bn) acquisition of US drugmaker Sepracor by Japan's Dainippon Sumitomo Pharma (DSP).

The all-cash purchase price represents a premium of nearly $5 (£3) per share above Sepracor's closing price on 1 September. Sepracor's board has unanimously approved the deal, under which the company will continue operating as a wholly-owned subsidiary of DSP.

"[Sepracor's] board was pleased with this offer," said Willkie Farr partner Bill Grant, who advised Sepracor on the deal alongside partners Adam Turteltaub and Russell Leaf. DSP will use Sepracor's distribution and marketing arms to introduce its drugs to American consumers, says Grant.

This is the second big pharma purchase the firm has handled this year. In April Willkie Farr advised Stiefel Laboratories on its $3.6bn (£2.2bn) acquisition by GlaxoSmithKline.

Paul Weiss partners Ariel Deckelbaum, Jeffrey Marell, Toby Myerson and Kaye Yoshino represented DSP. Talks between the two companies began last May, Myerson said. The next step is regulatory approval from the Federal Trade Commission, which DSP expects is forthcoming.

Sepracor, which makes the popular sleep aid Lunesta, has strong marketing and distribution arms that will help DSP gain a foothold in the US pharmaceuticals market.

Japanese pharmaceutical companies have been aggressively moving into the US market, driven by the strong yen and stagnant local drug market. In April 2008 Takeda Pharmaceutical acquired another Massachusetts-based firm, Millennium Pharmaceuticals, for $8.8bn (£5.4bn). Last September Shionogi purchased Sciele Pharma of Georgia for $1.4bn (£860m).

In other pharma-merger news, LEO Pharma has acquired Peplin for $287.5m (£176m) in cash. LEO, which is based in Denmark, was advised by Cooley Godward Kronish. Peplin is an Australian firm whose transactional work was handled by Fenwick & West.

This article first appeared on The Am Law Daily blog on americanlawyer.com.

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