Press Release 29 Mar 2012 Alkermes plc (NASDAQ: ALKS) today marked the official opening of its new global corporate headquarters in Ireland, located at Connaught House1 on Burlington Road in Dublin. Minister for Health, Dr. James Reilly TD, joined the Alkermes plc leadership team at a reception to commemorate the opening of the company’s new corporate headquarters. The company employs more than 400 people in Ireland at its manufacturing and drug development facility in Athlone, Co. Westmeath and at its global headquarters operation in Dublin, with more than 1,200 employees worldwide. Commenting at today’s event, Richard Pops, Chief Executive Officer of Alkermes plc, said: “Ireland has established a solid track record as the ideal location for many of the world’s leading pharmaceutical businesses. We see our Dublin base as important to the evolution of our business, both in our European markets and globally. We look forward to building a substantial biopharmaceutical business, based in Ireland, with the goal of bringing innovative medicines to the patients we serve.” Last September, the company announced a multiyear, multimillion-dollar manufacturing agreement for its Athlone plant with one of the world’s top ten pharmaceutical companies. Speaking at the opening ceremony, Minister James Reilly said: “I am delighted to welcome Alkermes to Ireland and wish the company every success in its continued development of innovative new products. I have no doubt that Alkermes has an important role to play both in the future success of our economy and in improving outcomes for patients.” Welcoming the official opening of Alkermes’ new global corporate headquarters in Dublin, Barry O’Leary, Chief Executive Officer of IDA Ireland said: “Ireland is a leading location for life sciences companies and home to 9 of the top 10 global pharmaceutical companies, with 7 of the top 10 pharmaceutical blockbuster products manufactured here. The continued growth and success of Alkermes further adds to Ireland’s reputation as a hub for the pharmaceutical sector. On behalf of IDA Ireland, I wish Alkermes ongoing success with this operation and offer the continued support of IDA Ireland.” Alkermes plc was formed following the merger of Alkermes, Inc. and Elan Drug Technologies (EDT), in September 2011. The company established its global headquarters in Ireland following the completion of the merger. For further information: Eilish Joyce, +353 87 791 4641 Jennifer Snyder, +1 781 609 6166 About Alkermes plc Alkermes plc is a fully integrated, global biopharmaceutical company that applies its scientific expertise and proprietary technologies to develop innovative medicines that improve patient outcomes. The company has a diversified portfolio of more than 20 commercial drug products and a substantial clinical pipeline of product candidates that address central nervous system (CNS) disorders such as addiction, schizophrenia and depression. Headquartered in Dublin, Ireland, Alkermes plc has an R&D center in Waltham, Massachusetts and manufacturing facilities in Athlone, Ireland; Gainesville, Georgia; and Wilmington, Ohio. For more information, please visit Alkermes’ website at www.alkermes.com. Note Regarding Forward-Looking Statements Certain statements set forth above may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Although the company believes that such statements are based on reasonable assumptions within the bounds of its knowledge of its business and operations, the forward-looking statements are neither promises nor guarantees; the company’s business and the other matters discussed by such forward-looking statements are subject to significant risk and uncertainties, and there can be no assurance that actual results or events will not differ materially from its expectations. These risks and uncertainties include the risks described in the company’s Registration Statement on Form S-1 (commission file number 333-179550), which was declared effective by the Securities and Exchange Commission (SEC) on March 2 , 2012, and in other filings made by the company with the SEC and which are available at the SEC’s website at www.sec.gov. The information contained in this press release is provided by the company as of the date hereof and, except as required by law, the company disclaims any intention or responsibility for updating any forward-looking information contained in this press release.