Horizon Pharma plc, a biopharmaceutical company, has received a Notice of Allowance from the United States Patent and Trademark Office for US patent application number 13/775,000 (US publication number 2013-0210914), entitled "Methods of Therapeutic Monitoring of Nitrogen Scavenging Drugs" that covers company's US approved product Ravicti (glycerol phenylbutyrate) oral liquid.

"Ravicti is the only FDA-approved oral liquid treatment for people with urea cycle disorders and this Notice of Allowance provides important new claims that strengthen our ability to protect this important medicine in the United States," said Timothy P. Walbert, chairman, president and chief executive officer, Horizon Pharma plc.

This Notice of Allowance concludes the substantive examination of the patent application and will result in the issuance of a US patent after administrative processes are completed. The US patent scheduled to issue from this application will expire in 2032. After issuance, Horizon plans to list the US patent in the US Food and Drug Administration's Approved Drug Products with Therapeutic Equivalence Evaluations, or Orange Book. This will be the fourth US patent listed in the Orange Book for Ravicti.

Ravicti is indicated for use as a nitrogen-binding agent for chronic management of adult and pediatric patients = 2 years of age with urea cycle disorders (UCDs) who cannot be managed by dietary protein restriction and/or amino acid supplementation alone. Ravicti must be used with dietary protein restriction and, in some cases, dietary supplements (e.g., essential amino acids, arginine, citrulline and protein-free calorie supplements).

Urea Cycle Disorders (UCDs) are inherited metabolic diseases caused by a deficiency of one of the enzymes or transporters that constitute the urea cycle. The urea cycle involves a series of biochemical steps in which ammonia, a potent neurotoxin, is converted to urea, which is excreted in the urine. UCD patients may experience episodes where they get symptoms from the ammonia in their blood being excessively high -- called hyperammonemic crises -- which may result in irreversible brain damage, coma or death. UCD symptoms may first occur at any age depending on the severity of the disorder, with more severe defects presenting earlier in life.