Paul W. Hoelscher (CFO) Andy Pasternak (CBO) Horizon Therapeutics plc was a biopharmaceutical company focused on researching, developing, and commercializing medicines that address critical needs for people impacted by rare and rheumatic diseases.

[8] In March 2015, the company acquired Hyperion Therapeutics for $1.1 billion, increasing Horizon's orphan disease drug portfolio.

[10] In September 2016, the company announced the acquisition of Raptor Pharmaceutical for $800 million, adding Procysbi and Quinsair to its rare drug portfolio.

[5] The company has cooperated with American Gastroenterological Association (AGA) Institute to launch a program named "Connect to Protect" which aims to help physicians and patients better understand non-steroidal anti-inflammatory drug (NSAID) risks.

[22] In March 2014, the company executed a corporate tax inversion to Ireland by acquiring Irish–based Vidara Therapeutics International for $660 million.

[24] In July 2015, the Wall Street Journal noted that Horizon were using their lower Irish corporate tax rate to acquire further U.S.–based life sciences firms (i.e.