Phenylbutyrate: uses, dosing, side effects & brands
Phenylbutyrate is a nitrogen binding agent sold in the U.S. under 3 brand and generic names, for sickle cell anemia, cystic fibrosis and myeloproliferative disorders. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Nitrogen Binding Agent
- Treats (across its forms)
- Sickle Cell Anemia, Cystic Fibrosis and Myeloproliferative Disorders
- Available as
- Tablet · Powder · Kit · Oral pellets
- Sold as
- 3 products — Buphenyl, Olpruva and Pheburane
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
How Pheburane is dosed
From the FDA label for Pheburane (application NDA216513). Other phenylbutyrate products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
PHEBURANE treatment should be supervised by a healthcare provider experienced in the treatment of UCDs. For administration, see full prescribing information. ( 2.1 , 2.4 ) The recommended dosage measured as sodium phenylbutyrate is: Patients weighing < 20 kg: 450–600 mg/kg/day of sodium phenylbutyrate orally. ( 2.1 ) Patients weighing ≥ 20 kg: 9.9–13.0 g/m 2 /day of sodium phenylbutyrate orally. ( 2.1 ) Monitor plasma ammonia levels to determine the need for dosage adjustment. ( 2.2 ) Monitor patients for potential neurotoxicity. ( 2.2 ) For patients with hepatic impairment, start at the lower end of the recommended dosing range. ( 2.3 ) 2.1 Recommended Dosage PHEBURANE treatment should be supervised by a healthcare provider experienced in the treatment of urea cycle disorders. The recommended dosage of PHEBURANE (measured as sodium phenylbutyrate) for patients with urea cycle disorders is: Patients weighing less than 20kg: 450 – 600 mg/kg/day of sodium phenylbutyrate orally. Divide the calculated total daily dose into three to six doses. Administer as three to six divided doses and take with food. Patients weighing greater than or equal to 20 kg: 9.9 – 13 g/m 2 /day of sodium phenylbutyrate orally. Divide the calculated total daily dose into three to six doses. Administer as three to six divided doses and take with food. The maximum dosage is 20 grams per day. Combine…
Everything below is the FDA label for Pheburane (oral pellets, kit). Phenylbutyrate is also sold as tablet and powder, and those are different medicines to take — follow the label for the one you were prescribed.
Pheburane side effects
The following adverse reactions associated with the use of sodium phenylbutyrate were identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily and from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Most common adverse reactions (incidence ≥ 3%) are amenorrhea or menstrual dysfunction (irregular menstrual cycles), decreased appetite, body odor and bad taste or taste aversion. Less Common Clinical Adverse Reactions Blood and lymphatic system disorders: aplastic anemia, ecchymoses Cardiac disorders : arrhythmia Gastrointestinal disorders : abdominal pain, decreased appetite, gastritis, nausea and vomiting, constipation, rectal bleeding, peptic ulcer disease, pancreatitis Metabolism and nutrition disorders: increased weight, edema Nervous system disorders : syncope, headache Psychiatric disorders : depression Renal and urinary disorders : renal tubular acidosis Skin and subcutaneous tissue disorders : rash Laboratory Adverse Reactions Blood and lymphatic system disorders : anemia, leukopenia and leukocytosis, thrombocytopenia, thrombocytosis Hepatobiliary disorders: hyperbilirubinemia, increased blood alkaline phosphatase, increased transaminases Metabolism and nutrition disorders: acidosis, alkalosis, hyperchloraemia,…
Who shouldn’t take Pheburane
None None. ( 4 )
Pheburane drug interactions
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 )] .
Every phenylbutyrate product we track (3)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | Not yet rated | Prescription | Tablet | No data | — | View → | |
| 2 | Not yet rated | Prescription | Kit | No data | — | View → | |
| 3 | Not yet rated | Prescription | Oral pellets | No data | — | View → |
What phenylbutyrate pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
Combination products containing phenylbutyrate
A combination is a different drug — different dosing, different warnings. It is listed here so you can find it, not so you can substitute it.
Can you crush or split phenylbutyrate?
At least one phenylbutyrateproduct is labelled to be swallowed whole — crushing an extended-release tablet releases the whole day’s dose at once. Which applies depends on the form you were given.
What each phenylbutyrate label says about crushing, splitting and chewingHow long phenylbutyrate keeps
The date on a sealed pack is not the only one: some phenylbutyrate labels start a second clock once the product is opened or mixed, as short as 45 days.
Does phenylbutyrate expire? The in-use limits and storage rules from its labelsRelated calculators
Frequently asked questions
What is Pheburane?
PHEBURANE (sodium phenylbutyrate) oral pellets is a nitrogen binding agent. Sodium phenylbutyrate is a white or yellowish-white powder, freely soluble in water and in methanol, and practically insoluble in methylene chloride.
What kind of drug is phenylbutyrate?
The FDA classifies phenylbutyrate as a nitrogen binding agent. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take phenylbutyrate with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run phenylbutyrate against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is phenylbutyrate sold under?
We track 3 phenylbutyrate-containing products in the U.S.: Buphenyl, Olpruva and Pheburane. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does phenylbutyrate come in?
Across the brands we track, phenylbutyrate is currently marketed as tablet, powder, kit and oral pellets, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic phenylbutyrate?
We do not currently list a generic-labelled phenylbutyrate product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Phenylbutyrate: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/phenylbutyrate
- MLA
- “Phenylbutyrate: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/phenylbutyrate.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for phenylbutyrate on DailyMed (NIH) ↗.