Urea Cycle Disorder Treatment with Glycerol Phenylbutyrate and Sodium Phenylbutyrate – Phase IV

Study of the Safety, Pharmacokinetics and Ammonia Control of RAVICTI® (Glycerol Phenylbutyrate) Oral Liquid and Sodium Phenylbutyrate in Phenylbutyrate Treatment Naïve Patients with Urea Cycle Disorders

Protocol Description

This international multi-center study compares the effects of glycerol phenylbutyrate and sodium phenylbutyrate to manage urea cycle disorders (UCDs). Rare genetic conditions, UCDs cause accumulation of high levels of ammonia in the blood, which can lead to brain damage and other serious problems. Glycerol phenylbutyrate, known by the trade name Ravicti® and sodium phenylbutyrate, known as Buphenyl®, work similarly by helping to remove unwanted ammonia from the body. Both Raviciti,  a liquid, and Buphenyl, a tablet or powder, can be taken orally or by feeding tube.

Study Level: Phase IV

Eligibility Criteria

Candidates must have a suspected or confirmed UCD diagnosis without having been treated over a long period of time with either of the study drugs.
Males and Females: All ages


By random selection, participants will be assigned to a treatment arm that starts with either Raviciti or Buphenyl to be taken 3 times a day for 4 weeks. After that, participants who started on Buphenyl will transition to Raviciti for 8 more weeks and those who started on Raviciti will continue on the drug. During the dosing periods, participants will return to the clinic for examinations, blood tests and other evaluations. A 12-week safety extension period will provide additional examinations and monitoring.
Visits: 13
Duration: About 25 weeks

Status: Open to Enrollment

Source(s) of Support

Horizon Therapeutics

Primary Investigator

Gerard Vockley, MD, PhD

Contact Information

For more information about the study or enrollment, please contact: 
Jessica Lindenberger, MSN, CRNP, FNP-C