DUBLIN, Ireland, and BRISBANE, Calif. — Horizon Pharma plc plans to acquire biopharmaceutical company Hyperion Therapeutics Inc. in a $1.1 billion cash deal.

Horizon said Monday that the agreement will increase its number of products from five to seven, notably through the addition of Ravicti and Buphenyl to its orphan business unit.

Ravicti and Buphenyl are medicines for people with urea cycle disorders (UCDs), a collection of inherited metabolic disorders that impact about 2,100 people in the United States with approximately 1,100 diagnosed. Net sales of the two medications totaled $113.6 million in 2014.

“The Hyperion acquisition will expand and diversify our product portfolio by adding two complementary orphan disease products, Ravicti and Buphenyl, and leverage as well as expand the existing infrastructure of our orphan disease business,” stated Timothy Walbert, chairman, president and chief executive officer of Horizon Pharma. “This transaction will be immediately accretive to adjusted EPS [earnings per share], and we expect the contribution of Ravicti and Buphenyl in 2016 will add approximately $100 million to our adjusted EBITDA [earnings before interest, taxes, depreciation and amortization], including cost synergies contributing greater than $50 million. Additionally, this acquisition further accelerates our near- and long-term sales and adjusted EBITDA growth.”

The acquisition deal is structured as an all-cash tender offer for all the issued and outstanding shares of Hyperion common stock at $46 per share, followed by a merger in which each remaining untendered share of Hyperion common stock would be converted into the $46-per-share cash consideration paid in the tender offer.

Horizon said the proposed transaction has been unanimously approved by both companies’ boards of directors. Pending customary conditions, including the tender of a majority of the outstanding Hyperion shares, the transaction is expected to close in the second quarter.

“During the last two years, we have solidified our position in the orphan disease space and made significant progress in bringing life-changing medicines to people with urea cycle disorders,” commented Donald Santel, president and CEO of Hyperion Therapeutics. “I would like to thank my colleagues for their tireless commitment to advancing the clinical development and understanding of Ravicti, Buphenyl and urea cycle disorders. Horizon shares our commitment, and I’m confident that the strength of its existing orphan business unit will continue to expand the reach of these important medicines to more patients impacted by these disorders.”