No

Urea Cycle Disorder (UCD) Treatment Agent

Adjunctive therapy in the chronic management of patients with urea cycle disorder involving deficiencies of carbamoylphosphate synthetase, ornithine transcarbamylase, or argininosuccinic acid synthetase

C

Previous hypersensitivity to phenylbutyrate, severe hypertension, heart failure or renal dysfunction; phenylbutyrate is not indicated in the treatment of acute hyperammonemia

Since no studies have been conducted in pregnant women, sodium phenylbutyrate should be used cautiously during pregnancy; each 1 gram of drug contains 125 mg of sodium and, therefore, should be used cautiously, if at all, in patients who must maintain a low sodium intake

>10%: Endocrine & metabolic: Amenorrhea, menstrual dysfunction

1% to 10%:

Gastrointestinal: Anorexia, abnormal taste

Miscellaneous: Offensive body odor

Store at room temperature (59°F to 86°F); after opening, containers should be kept tightly closed

Sodium phenylbutyrate is a prodrug that, when given orally, is rapidly converted to phenylacetate, which is in turn conjugated with glutamine to form the active compound phenylacetyglutamine; phenylacetyglutamine serves as a substitute for urea and is excreted in the urine whereby it carries with it 2 moles of nitrogen per mole of phenylacetyglutamine and can thereby assist in the clearance of nitrogenous waste in patients with urea cycle disorders

Powder: Patients weighing <20 kg: 450-600 mg/kg/day or 9.9-13 g/m²/day, administered in equally divided amounts with each meal or feeding, four to six times daily; safety and efficacy of doses >20 g/day has not been established

Tablet: Children >20 kg and Adults: 450-600 mg/kg/day or 9.9-13 g/m²/day, administered in equally divided amounts with each meal; safety and efficacy of doses >20 g/day have not been established

No information available to require special precautions

No effects or complications reported

It is important that patients understand and follow the dietary restrictions required when treating this disorder, the medication must be taken in strict accordance with the prescribed regimen and the patient should avoid altering the dosage without the prescriber's knowledge; the powder formulation has a very salty taste

Powder: 3.2 g [sodium phenylbutyrate 3 g] per teaspoon (500 mL, 950 mL); 9.1 g [sodium phenylbutyrate 8.6 g] per tablespoon (500 mL, 950 mL)

Tablet: 500 mg

Brusilow SW, "Phenylacetylglutamine May Replace Urea as a Vehicle for Waste Nitrogen Excretion," Pediatr Res, 1991, 29(2):147-50.

Maestri NE, Brusilow SW, Clissold DB, et al, "Long-Term Treatment of Girls With Ornithine Transcarbamylase Deficiency," N Engl J Med, 1996, 335(12):855-9.