Horizon Pharma plc (NASDAQ: HZNP), a biopharmaceutical company focused on improving patients' lives by identifying, developing, acquiring and commercializing differentiated and accessible medicines that address unmet medical needs, and its affiliate, Horizon Therapeutics Limited, today announced that the European Commission (EC) has adopted a binding decision to approve RAVICTI® (glycerol phenylbutyrate) Oral Liquid for use as an adjunctive therapy for chronic management of adult and pediatric patients two months of age and older with six subtypes of Urea Cycle Disorders (UCDs). This decision follows the Positive Opinion previously adopted on September 24, 2015 by the Committee for Medicinal Products for Human Use of the European Medicines Agency. The approval authorizes Horizon to market RAVICTI in all 28 Member States of the European Union (EU), and the Centralized marketing authorization will form the basis for recognition by the Member States of the European Economic Area (EEA), namely Norway, Iceland and Liechtenstein, for the product to be placed on the market.

As RAVICTI is a designated orphan medicinal product containing a new active substance, it will benefit from a period of 10 years of regulatory data/market protection with a possibility of extension to 11 years and a period of 10 years of orphan market exclusivity concurrently applied to each of the approved six sub-types of the UCDs.

UCDs are metabolic diseases that affect a specific enzyme or transporter of the urea cycle, causing heightened levels of ammonia in the blood stream. Symptoms of the disorder can begin at any age, with more severe defects beginning early in life. UCD patients may experience episodes, called hyperammonemic crises, when ammonia levels in the blood become excessively high, which can result in irreversible brain damage, coma or death.

'The approval of RAVICTI in the European Union and the European Economic Area represents a significant milestone for Horizon Pharma as we expand our business globally,' said Timothy P. Walbert, chairman, president and chief executive officer, Horizon Pharma plc. 'With this approval, we will now focus on developing country-by-country plans to make RAVICTI available to people with urea cycle disorders throughout Europe.'