Clinical trial NCT00345605: Arginine and Buphenyl in Patients With Argininosuccinic Aciduria (ASA), a Urea Cycle Disorder
Official title: A Randomized, Double-Blind, Crossover Study of Sodium Phenylbutyrate and Low-Dose Arginine Compared to High-Dose Arginine Alone on Liver Function, Ureagenesis and Subsequent Nitric Oxide Production in Patients With Argininosuccinic Aciduria
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE2
Conditions: Argininosuccinic Aciduria
Amino Acid Metabolism, Inborn Errors
Urea Cycle Disorders
Keywords: Argininosuccinic Acid Lyase Deficiency
ASA
Lead sponsor: Baylor College of Medicine
Sponsor class: OTHER
Collaborators: name: Office of Rare Diseases (ORD)
name: Rare Diseases Clinical Research Network
name: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
First posted: 2006-06-28
Enrollment: 12
Sex: ALL
Minimum age (years): 5
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: Urea cycle disorders are inherited illnesses in which the body does not produce enough of the chemicals that remove ammonia, a byproduct of protein metabolism, from the blood stream. Elevated ammonia levels can lead to brain damage and death. Argininosuccinic aciduria (ASA) is a type of urea cycle disorder that is characterized specifically by high levels of argininosuccinic acid, a chemical involved in the urea cycle. People with ASA are at risk for serious liver damage, which may be due to the elevated levels of argininosuccinic acid. Sodium phenylbutyrate (Buphenyl-TM) is a drug that has been used to treat other types of urea cycle disorders. This study will evaluate whether Buphenyl-TM in conjunction with decreased arginine dose (in addition to a normal regimen of protein) will improve short-term liver function and decrease plasma citrulline and ASA levels in people with ASA.

Detailed description: The cause of liver damage in people with ASA is unknown. However, because ASA is the only urea cycle disorder that is characterized by both liver damage and elevated levels of argininosuccinic acid, researchers believe that the elevated acid levels cause the liver damage. Common treatments for urea cycle disorders include a low-protein diet and arginine supplementation, which, when combined, help to decrease ammonia levels in the blood. Buphenyl-TM may aid in lowering ammonia and argininosuccinic acid levels. Although Buphenyl-TM has been FDA-approved for use in people with some types of urea cycle disorders, there is little information on the effectiveness of the drug in children with ASA. This study will evaluate whether treatment of ASA patients with Buphenyl-TM in conjunction with lowered doses of arginine improves liver function as measured by short-term assessment of synthetic activity and the use of stable isotope tracers to assess ureagenesis and nitric oxide production.

Initially, participants in this double-blind, placebo-controlled, crossover study will undergo a 3-day washout period during which no Buphenyl-TM will be given. They will then be randomly assigned to one of two groups: either Buphenyl-TM (500 mg/kg/day or 10 grams/m2) and arginine (100 mg/kg/day or 2 grams/m2)), or arginine alone (500 mg/kg/day or 10 grams/m2). Participants will remain on this initial treatment arm for 1 week, at the conclusion of which an assessment of hepatic synthetic function, ureagenesis, and nitric oxide production will be performed. After this assessment, participants will undergo a second 3-day washout and then crossover to the other treatment arm for 1 week. At the end of the 1-week treatment period, a second assessment will be performed. During the washout period before each treatment period, no Buphenyl-TM will be administered, and arginine will be administered at the standard therapeutic dose of 500 mg/kg/day or 10 grams/2.

Eligibility criteria: Inclusion Criteria:

* Has confirmed diagnosis of ASA by amino acid or enzyme assay
* Has a history of adequate compliance to the diet and treatment
* Able to take oral or G-tube medication
* Able to perform 24 hour urine collection
* Agrees to travel to Baylor College of Medicine
* If female, of child bearing potential, and sexually active, agrees to use an acceptable method of birth control
* Greater than 5 years of age

Exclusion Criteria:

* Has a history of congestive heart failure, severe renal insufficiency, or any condition that causes sodium retention or edema
* Currently taking Probenecid, Haloperidol, Valproate or oral corticosteroids
* Pregnant or lactating
* Currently being treated for an acute illness
* Has co-morbid associations causing difficulties in the detection of hyperammonemic episodes, liver damage, or difficulties in the diet compliance
* Has known hypersensitivity to sodium phenylbutyrate
* Has taken any experimental medication within the last 30 days
* Has renal insufficiency with creatinine greater than 1.5 mg/dl at screening

Primary outcomes:
measure: Measures of Liver Function: AST and ALT
timeFrame: Measured after each 1-week treatment period
measure: Measures of Liver Function: PT and PTT
timeFrame: Measured after each 1-week treatment period
measure: Measures of Liver Function: Coagulation Factors
timeFrame: Measured after each 1-week treatment period
measure: Measures of Liver Function: INR
timeFrame: Measured after each 1-week treatment period
Secondary outcomes:
measure: Argininosuccinic Acid Levels
timeFrame: Measured after each 1-week treatment period
measure: Arginine Levels
timeFrame: Measured after each 1-week treatment period
measure: Urea Production Rate
timeFrame: Measured after each 1-week treatment period
Other outcomes:
Locations:
city: Houston
country: United States
facility: Baylor College of Medicine
state: Texas
Study officials:
affiliation: Baylor College of Medicine
name: Brendan Lee, MD, PhD
role: PRINCIPAL_INVESTIGATOR
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