UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT
Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 6, 2014

(Exact Name of Registrant as Specified in Charter)

Registrant’s telephone number, including area code: (301) 961-3400

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01. Other Events.

Under the terms of the February 19, 2009 agreement between the Company’s affiliate and Abbott Japan Co. Ltd. (“Abbott Japan”) to develop and commercialize lubiprostone in Japan for the treatment of CIC, Abbott Japan will pay a commercial milestone of $2.5 million within forty-five (45) days after the end of the month during which the first occurrence of annual net sales of lubiprostone in Japan exceeds JPY5,000,000,000. After confirming the October 2014 notification by Abbott Japan that annual net sales had exceeded JPY5,000,000,000 by the end of September 2014, the Company invoiced Abbott Japan for the $2.5 million commercial milestone on October 6, 2014.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.