Sodium phenylbutyrate

FDA label, Medunik USA, oral, effective 2026-07-17. Full label on DailyMed

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Quoted from the FDA label. Product labels differ by manufacturer and change over time; confirm against the label for the product you are using.

Dosing in kidney impairment

Renal Impairment No studies with PHEBURANE were conducted in subjects with renal impairment. Monitor plasma ammonia levels when starting patients with impaired renal function on PHEBURANE [see Clinical Pharmacology].

Dosing in liver impairment

Dosage Adjustment in Patients with Hepatic Impairment For patients with hepatic impairment, start at the lower end of the recommended dosing range and maintain patients on the lowest dose necessary to control plasma ammonia levels [see Use in Specific Populations] .

Preparation and administration

Administration Instructions For oral administration only. Administration via gastrostomy or nasogastric tubes has not been evaluated. Schedule PHEBURANE dosages at the same time as food consumption (meal or snack). Use the calibrated dosing spoon to measure PHEBURANE oral pellets. The dosing spoon is directly calibrated in grams of sodium phenylbutyrate.

Swallow the coated oral pellets with a drink (e.g., water, fruit juices, protein-free infant formulas) or sprinkle onto spoonful of apple sauce or carrot puree. Do not chew PHEBURANE oral pellets directly or mix into liquids. Swallow immediately to minimize dissolution of coating. Administration of PHEBURANE oral pellets with other foods has not been studied and is not recommended.

Additionally, administration with soft food is only recommended in patients old enough to consume soft foods.

Drug interactions

Check sodium phenylbutyrate against a medication list
Label text (3 paragraphs)

Valproic Acid, Haloperidol, or Corticosteroids : May increase plasma ammonia level; monitor ammonia levels closely. ( 7.1 ) Probenecid : May inhibit renal excretion of metabolites of PHEBURANE including phenylacetate and phenylacetylglutamine; monitor for potential neurotoxicity. ( 7.2 )

7.1 Potential for Other Drugs to Affect Ammonia Corticosteroids Use of corticosteroids may cause the breakdown of body protein and increase plasma ammonia levels. Valproic Acid and Haloperidol Hyperammonemia may be induced by haloperidol and by valproic acid. Monitor plasma ammonia levels closely when PHEBURANE is used concomitantly with corticosteroids, valproic acid, or haloperidol.

7.2 Effects of Other Drugs on PHEBURANE Probenecid Probenecid may inhibit renal excretion of the metabolites of PHEBURANE including phenylacetate and phenylacetylglutamine. Monitor patients for potential neurotoxicity and measure plasma phenylacetate and phenylacetylglutamine levels when probenecid is used concomitantly with PHEBURANE [see Dosage and Administration ( 2.2 )] .

Contraindications

None None. ( 4 )

Pregnancy and lactation

Pregnancy

8.1 Pregnancy Risk Summary Available data with sodium phenylbutyrate use in pregnant women are insufficient to identify a drug associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. Animal reproduction studies have not been conducted with sodium phenylbutyrate. Based on published animal data, phenylacetate may be neurotoxic to the developing brain (see Data ) . There are serious risks to the mother and fetus associated with untreated urea cycle disorders during pregnancy which can result in serious morbidity and mortality to the mother and fetus (see Clinical Considerations ) .

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal Risk Pregnancy is a time of increased metabolic demand which increases the risk for hyperammonemic episodes when metabolic demands are not met.

Hyperammonemic episodes in pregnancy are associated with impaired cognition in the mother and an increased risk of maternal and fetal death. Data In rats, intrauterine exposure to phenylacetate produced lesions in the neonatal brain in layer 5 of the cortical pyramidal cells; dendritic spines were longer and thinner than normal and reduced in number.

For breastfeeding, also see LactMed (National Library of Medicine), which summarizes milk levels and infant effects.

Supply and cost

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