Upsher-Smith Laboratories Inc. announced an agreement to acquire Proximagen Group PLC, a London-based development-stage drug company in a deal valued at $346.7 million. The deal's value could increase to $554.7 million depending on commercialization prospects of two new Proximagen drugs.

UPSHER-SMITH LABORATORIES INC.

Headquarters: Maple Grove

Founded: 1919

Chairman: Ken Evenstad

President and CEO: Mark Evenstad

Business: Family-owned and privately held specialty pharmaceutical company focuses on innovative uses of generic and branded-generic drugs, especially drugs treating disorders of the central nervous system.

Employees: 600

2011 sales: $451 million

PROXIMAGEN GROUP PLC

Headquarters: London

Nonexecutive chairman: Peter Allen

CEO: Kenneth Mulvany

2011 sales: $281,000

2011 earnings: $7.9 million

Employees: 41

Business: Biotechnology company that develops novel drugs for the central nervous system and inflammatory diseases. Publicly traded on London Stock Exchange. Proximagen was granted 24 patents in 2011 and has more than 285 patents.