Sodium phenylbutyrate

Sodium phenylbutyrate is an FDA-registered drug product whose active ingredient is SODIUM PHENYLBUTYRATE. It is labelled by Navinta LLC taken by oral and marketed as a human prescription drug product. Identifiers on file: NDC 68475-011, application ANDA220418, label effective 20260709. It is one of 4 FDA drug label records sharing the active ingredient SODIUM PHENYLBUTYRATE. This page reproduces the FDA-approved label text so you can check what a product is, who makes it and how it is supplied before discussing it with a pharmacist or prescriber.

Across FDA labelling, products containing SODIUM PHENYLBUTYRATE are most often described in connection with: sodium phenylbutyrate, hyperammonemic encephalopathy, dietary protein, deficiency patients, ornithine transcarbamylase, essential amino, carbamylphosphate synthetase, argininosuccinic acid. Wording differs between labels, and the full indications section on this page takes precedence when it is present.

INDICATIONS AND USAGE Sodium phenylbutyrate tablets are indicated as adjunctive therapy in the chronic management of patients with urea cycle disorders involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS). It is indicated in all patients with neonatal-onset deficiency (complete enzymatic deficiency, presenting within the first 28 days of life). It is also indicated in patients with late-onset disease (partial enzymatic deficiency, presenting after the first month of life) who have a history of hyperammonemic encephalopathy. It is important that the diagnosis be made early and treatment initiated immediately to improve survival. Any episode of acute hyperammonemia should be treated as a life-threatening emergency. Sodium phenylbutyrate tablets must be combined with dietary protein restriction and, in some cases, essential amino acid supplementation. (See Nutritional Supplementation subsection of the DOSAGE AND ADMINISTRATION section.) Previously, neonatal-onset disease was almost universally fatal within the first year of life, even when treated with peritoneal dialysis and essential amino acids or their nitrogen-free analogs. However, with hemodialysis, use of alternative waste nitrogen excretion pathways (sodium phenylbutyrate, sodium benzoate, and sodium phenylacetate), dietary protein restriction, and, in some cases, essential amino acid supplementation, the survival rate in newborns diagnosed after birth but within the first month of life is almost 80%. Most deaths have occurred during an episode of acute hyperammonemic encephalopathy. Patients with neonatal-onset disease have a high incidence of mental retardation. Those who had IQ tests administered had an incidence of mental retardation as follows: ornithine transcarbamylase deficiency, 100% (14/14 patients tested); argininosuccinic acid synthetase deficiency, 88% (15/17 patients tested); and carbamylphosphate synthetase deficiency, 57% (4/7 patients tested). Retardation was severe in the majority of the retarded patients. In patients diagnosed during gestation and treated prior to any episode of hyperammonemic encephalopathy, survival is 100%, but even in these patients, most subsequently demonstrate cognitive impairment or other neurologic deficits. In late-onset deficiency patients, including females heterozygous for ornithine transcarbamylase deficiency, who recover from hyperammonemic encephalopathy and are then treated chronically with sodium phenylbutyrate and dietary protein restriction, the survival rate is 98%. The two deaths in this group of patients occurred during episodes of hyperammonemic encephalopathy. However, compliance with the therapeutic regimen has not been adequately documented to allow evaluation of the potential for sodium phenylbutyrate and dietary protein restriction to prevent mental deterioration and recurrence of hyperammonemic encephalopathy if carefully adhered to. The majority of these patients tested (30/46 or 65%) have IQ's in the average to low average/borderline mentally retarded range. Reversal of preexisting neurologic impairment is not likely to occur with treatment and neurologic deterioration may continue in some patients. Even on therapy, acute hyperammonemic encephalopathy recurred in the majority of patients for whom the drug is indicated. Sodium phenylbutyrate tablets may be required lifelong unless orthotopic liver transplantation is elected. (See CLINICAL PHARMACOLOGY, Pharmacodynamics subsection for the biochemical effects of sodium phenylbutyrate).

DOSAGE AND ADMINISTRATION For oral use only. The use of sodium phenylbutyrate Tablets is indicated for children weighing more than 20 kg and for adults. The usual total daily dose of sodium phenylbutyrate tablets for patients with urea cycle disorders is 450–600 mg/kg/day in patients weighing less than 20 kg, or 9.9–13.0 g/m 2 /day in larger patients. The tablets are to be taken in equally divided amounts with each meal or feeding (i.e., three to six times per day). The effect of food on sodium phenylbutyrate has not been determined. The safety or efficacy of doses in excess of 20 grams (40 tablets) per day has not been established. NUTRITIONAL MANAGEMENT To promote growth and development, plasma levels of ammonia, arginine, branched-chain amino acids, and serum protein should be maintained within normal limits while plasma glutamine is maintained at levels less than 1,000 μmol/L. Minimum daily protein intake for a patient of a particular age should be taken from, for example, "Recommended Dietary Allowances", 10th ed., Food and Nutrition Board, National Academy of Sciences, 1989. The allocation of dietary nitrogen into natural protein and essential amino acids is a function of age, residual urea cycle enzyme activity, and the dose of sodium phenylbutyrate. At the recommended dose of sodium phenylbutyrate, it is suggested that infants with neonatal-onset CPS and OTC deficiencies initially receive a daily dietary protein intake limited to approximately 1.6 g/kg/day for the first 4 months of life. If tolerated, the daily protein intake may be increased to 1.9 g/kg/day during this period. Protein tolerance will decrease as the growth rate decreases, requiring a reduction in dietary nitrogen intake. From 4 months to 1 year of age, it is recommended that the infant receive at least 1.4 g/kg/day, but 1.7 g/kg/day is advisable. From 1 to 3 years of age, the protein intake should not be less than 1.2 g/kg/day; 1.4 g/kg/day is advisable during this period. For neonatal-onset patients with carbamylphosphate synthetase deficiency or ornithine transcarbamylase deficiency who are at least 6 months of age, it is recommended that the daily protein intake be equally divided between natural protein and supplemental essential amino acids. Patients with argininosuccinic acid synthetase deficiency and those with late-onset disease (partial deficiencies, including females heterozygous for ornithine transcarbamylase), initially may receive a diet containing the age-determined minimal daily natural protein allowance. The protein intake may be increased as tolerated and determined by plasma glutamine and other amino acid levels. However, many patients with partial deficiencies avoid dietary protein. Citrulline supplementation is required and recommended for patients diagnosed with neonatal-onset deficiency of carbamylphosphate synthetase or ornithine transcarbamylase; citrulline daily intake is recommended at 0.17 g/kg/day or 3.8 g/m 2 /day. The free-base form of arginine may be used instead of citrulline in patients with -milder forms of carbamylphosphate synthetase and ornithine transcarbamylase deficiency (daily intake is recommended at 0.17 g/kg/day or 3.8 g/m 2 /day). Arginine supplementation is needed for patients diagnosed with deficiency of argininosuccinic acid synthetase; arginine (free base) daily intake is recommended at 0.4–0.7 g/kg/day or 8.8–15.4 g/m 2 /day. If caloric supplementation is indicated, a protein-free product is recommended. Caloric intake should be based upon the "Recommended Dietary Allowances", 10th ed., Food and Nutrition Board, National Research Council, National Academy of Sciences, 1989.

CONTRAINDICATIONS Sodium phenylbutyrate tablets should not be used to manage acute hyperammonemia, which is a medical emergency.

WARNINGS Each sodium phenylbutyrate Tablet contains 62 mg of sodium (9.2% w/w) (corresponding to 124 mg of sodium per gram of sodium phenylbutyrate [12.4% w/w]). Sodium phenylbutyrate tablet should be used with great care, if at all, in patients with congestive heart failure or severe renal insufficiency, and in clinical states in which there is sodium retention with edema. Because sodium phenylbutyrate is metabolized in the liver and kidney, and phenylacetylglutamine is primarily excreted by the kidney, use caution when administering the drug to patients with hepatic or renal insufficiency or inborn errors of beta oxidation. Probenecid is known to inhibit the renal transport of many organic compounds, including hippuric acid, and may affect renal excretion of the conjugated product of sodium phenylbutyrate as well as its metabolite. Use of corticosteroids may cause the breakdown of body protein and increase plasma ammonia levels.

ADVERSE REACTIONS The assessment of clinical adverse events came from 206 patients treated with sodium phenylbutyrate. Adverse events (both clinical and laboratory) were not collected systematically in these patients, but were obtained from patient visit reports by the 65 co-investigators. Causality of adverse effects is sometimes difficult to determine in this patient population because they may result from either the underlying disease, the patient's restricted diet, intercurrent illness, or sodium phenylbutyrate. Furthermore, the rates may be underestimated because they were reported primarily by parent or guardian and not the patient. Clinical Adverse Events In female patients, the most common clinical adverse event reported was amenorrhea/menstrual dysfunction (irregular menstrual cycles), which occurred in 23% of the menstruating patients. Decreased appetite occurred in 4% of all patients. Body odor (probably caused by the metabolite, phenylacetate) and bad taste or taste aversion were each reported in 3% of patients. Other adverse events reported in 2% or fewer patients were: Gastrointestinal : abdominal pain, gastritis, nausea and vomiting; constipation, rectal bleeding, peptic ulcer disease, and pancreatitis each occurred in one patient. Hematologic : aplastic anemia and ecchymoses each occurred in one patient. Cardiovascular : arrhythmia and edema each occurred in one patient. Renal : renal tubular acidosis Psychiatric : depression Skin : rash Miscellaneous : headache, syncope, and weight gain Neurotoxicity was reported in cancer patients receiving intravenous phenylacetate, 250–300 mg/kg/day for 14 days, repeated at 4-week intervals. Manifestations were predominately somnolence, fatigue, and lightheadedness; with less frequent -headache, dysgeusia, hypoacusis, disorientation, impaired memory, and exacerbation of a pre-existing neuropathy. These adverse events were mainly mild in severity. The acute onset and reversibility when the phenylacetate infusion was discontinued suggest a drug effect. Laboratory Adverse Events: In patients with urea cycle disorders, the frequency of laboratory adverse events by body system were: Metabolic : acidosis (14%), alkalosis and hyperchloremia (each 7%), hypophosphatemia (6%), hyperuricemia and hyperphosphatemia (each 2%), and hypernatremia and hypokalemia (each 1%). Nutritional : hypoalbuminemia (11%) and decreased total protein (3%). Hepatic : increased alkaline phosphatase (6%), increased liver transaminases (4%), and hyperbilirubinemia (1%). Hematologic: anemia (9%), leukopenia and leukocytosis (each 4%), thrombocytopenia (3%), and thrombocytosis (1%). The clinician is advised to routinely perform urinalysis, blood chemistry profiles, and hematologic tests.

FDA lists 4 drug label records with SODIUM PHENYLBUTYRATE as the active ingredient. The most common dosage forms and the manufacturers with the most records are summarised below; strengths, pack sizes and inactive ingredients can still differ between apparently similar products.

4 FDA recall record(s) match this product name or manufacturer. A match means the firm or product name appears in the enforcement report; confirm lot numbers and dates against the official FDA notice before acting.

What is Sodium phenylbutyrate used for?
INDICATIONS AND USAGE Sodium phenylbutyrate tablets are indicated as adjunctive therapy in the chronic management of patients with urea cycle disorders involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS). It is indicated in all patients with neonatal-onset deficiency (complete enzymatic deficiency, presenting …

Who makes Sodium phenylbutyrate?
Navinta LLC is the labeler of record for Sodium phenylbutyrate. 4 FDA label records share the active ingredient SODIUM PHENYLBUTYRATE, so generic and branded versions may come from different companies; the manufacturer named on your pack is the one that matters for any enquiry.

What form does Sodium phenylbutyrate come in?
administered by oral. Strengths and pack sizes vary by label, so compare the NDC on your pack with the identifier listed on this page.

Is Sodium phenylbutyrate prescription or over-the-counter?
The FDA label for this product is recorded as human prescription drug. Marketing status can differ between strengths and countries, so check the dispensing rules where you live.

Are there other products containing SODIUM PHENYLBUTYRATE?
Yes. 4 FDA drug label records list SODIUM PHENYLBUTYRATE as the active ingredient. Products with the same active ingredient can usually be substituted only when a prescriber or pharmacist confirms it is appropriate.

Has Sodium phenylbutyrate been recalled?
4 FDA recall record(s) match this product name or manufacturer. Review the recall and safety notices section on this page and confirm lot numbers against the official FDA enforcement report.

Where does this information come from?
All content is reproduced from FDA Structured Product Labelling data via openFDA. It is provided for identification and reference only and is not medical advice.