AcelRx Pharmaceuticals, a specialty pharmaceutical company focused on the development and commercialization of innovative therapies for use in medically supervised settings, agreed to acquire Tetraphase Pharmaceuticals, a biopharmaceutical company, for $37m and $16m potentially payable. Tetraphase stockholders will receive, for each share of Tetraphase common stock, $0.59 in cash and 0.7409 shares of AcelRx common stock. "AcelRx is financially disciplined, and while we continue to recognize the merits of an AcelRx and Tetraphase combination, we do not believe that any further increases to our offer would be in the best interests of our stockholders. As a result, we have decided not to further increase our offer and will focus on other exciting opportunities to expand and diversify our product portfolio and create a platform for growth with other potential collaboration partners," Vince Angotti, AcelRx CEO.