Prescription medicine
Sodium phenylbutyrate Brand names: Olpruva, Buphenyl, Pheburane
Sodium phenylbutyrate (Buphenyl) is a prescription medicine with an FDA approval on record since 1996. FDA's NDC Directory lists it from 4 generic labelers.
- Generic listed
Check it at the source: the sodium phenylbutyrate FDA label on DailyMed (effective July 17, 2026, Medunik USA); the NDA 20573 record on Drugs@FDA; every sodium phenylbutyrate label on DailyMed.
Highlights of the record
FDA label of July 17, 2026; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026
Used for
From the label: indications and usagePHEBURANE is indicated as adjunctive therapy to standard of care, which includes dietary management, for the chronic management of adult and pediatric patients with urea cycle disorders (UCDs), involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC) or argininosuccinic acid synthetase (AS).
Forms and strengths
- 500 mg
- 0.94 g/g
- 483 mg/g
Kit; tablet; powder; pellet.
On the market
- Earliest approval on file
- April 30, 1996 Buphenyl, Horizon Therap Us; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- 6 first November 18, 2011; 4 with a marketed status in Drugs@FDA
- Labelers listed (NDC)
- 7 of which 4 under generic applications, 3 under brand applications, repackagers included
- Last listed patent
- October 17, 2036 Olpruva for oral suspension; not a generic launch date
Supply and safety
- Pharmacy cost (NADAC)
- Not in the survey
- Shortage (FDA)
- No current entry
- Recalls by its makers (FDA)
- 2 since 2021 0 Class I among all firms' recalls; latest September 21, 2021
- FAERS reports
- 420 through July 30, 2026
What is sodium phenylbutyrate used for?
From the label: indications and usagePHEBURANE is indicated as adjunctive therapy to standard of care, which includes dietary management, for the chronic management of adult and pediatric patients with urea cycle disorders (UCDs), involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC) or argininosuccinic acid synthetase (AS). Limitations of Use Episodes of acute hyperammonemia may occur in patients while on PHEBURANE. PHEBURANE is not indicated for the treatment of acute hyperammonemia, which can be a life-threatening medical emergency that requires rapid acting interventions to reduce plasma ammonia levels. […]
FDA pharmacologic class: Nitrogen Binding Agent.
Source: FDA drug label (PHEBURANE), Medunik USA, effective July 17, 2026 (SPL set d15f2cbf-4d22-40b5-8ef9-16b9d323a7f9), via openFDA; the full label on DailyMed
Is there a generic for sodium phenylbutyrate (Buphenyl)?
The FDA approved the first generic sodium phenylbutyrate on November 18, 2011. 6 generic applications are approved; 4 of them carry a current (not discontinued) marketing status in Drugs@FDA; that status is not evidence that the generic is on sale.
FDA's NDC Directory lists sodium phenylbutyrate from 4 labelers under a generic (ANDA) application and from 3 brand labelers. A listing means the company has registered the product for sale; it does not show that every pharmacy stocks it.
The Orange Book lists no patent for Buphenyl powder; a patent listed only for Olpruva for oral suspension runs to October 17, 2036. A patent or exclusivity date is not the date a generic goes on sale: court cases and settlements move it either way.
- 1996 earliest approval on file
- 2011 first generic approved
- 2036 last listed patent
- red ticks recalls
Source: Drugs@FDA, FDA NDC Directory and the Orange Book (openFDA bulk files, October 8, 2026)
Has sodium phenylbutyrate been recalled?
The FDA's Enforcement Report lists 2 recalls naming sodium phenylbutyrate since 2021: 0 Class I (the most serious), 2 Class II, 0 Class III; 0 still ongoing. A recall names products and lots, not every product of the medicine.
| Started | Class | Company | Reason |
|---|---|---|---|
| September 21, 2021 | Class II | SigmaPharm Laboratories LLC | Failed Impurities/Degradation Specifications; Out of Specification impurity results obtained during routine testing. |
| August 13, 2021 | Class II | SigmaPharm Laboratories LLC | Failed Impurities Specifications: Out of Specification impurity results obtained during routine testing. |
Source: FDA Enforcement Report (drug recalls) via openFDA, through October 8, 2026
What does the sodium phenylbutyrate label say about other medicines?
The sodium phenylbutyrate label names 4 other medicines in its interaction, contraindication or warning sections. The labels of 1 other medicine name sodium phenylbutyrate. The sentences are the labels' own; a label lists what its studies and reports found, not every interaction.
| Medicine named | Section | What the label says |
|---|---|---|
| Divalproex | drug interactions | DRUG INTERACTIONS Valproic Acid, Haloperidol, or Corticosteroids: May increase plasma ammonia level; monitor ammonia levels closely. |
| Haloperidol | drug interactions | DRUG INTERACTIONS Valproic Acid, Haloperidol, or Corticosteroids: May increase plasma ammonia level; monitor ammonia levels closely. |
| Probenecid | drug interactions | Drugs on PHEBURANE Probenecid Probenecid may inhibit renal excretion of the metabolites of PHEBURANE including phenylacetate and phenylacetylglutamine. |
| Valproic acid | drug interactions | DRUG INTERACTIONS Valproic Acid, Haloperidol, or Corticosteroids: May increase plasma ammonia level; monitor ammonia levels closely. |
Other labels that name sodium phenylbutyrate
Source: FDA drug label (PHEBURANE), Medunik USA, effective July 17, 2026 (SPL set d15f2cbf-4d22-40b5-8ef9-16b9d323a7f9), via openFDA; the full label on DailyMed
What do FAERS reports show for sodium phenylbutyrate?
The FDA Adverse Event Reporting System holds 420 reports that list sodium phenylbutyrate among the medicines taken, through July 30, 2026, each a report of something that happened, not proof the medicine caused it; 84 are coded as a death and 164 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is.
The most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026
What next?
- Other nitrogen binding agents
- the pharmacologic class, with prices and generics
- Sodium phenylbutyrate side effects
- the label's list beside FAERS reports
- Check an interaction
- what two or more labels say about each other