Sodium phenylbutyrate
Ammonaps, Pheburane · ATC code A16AX03
Also known as: Sodyum fenilbutirat
- Key facts
- Active substance
- Sodium phenylbutyrate
- ATC code
- A16AX03
- Authorisation
- centrally authorised across the EU (EMA)
- Dosage forms
- AMMONAPS 500 mg tablets. · AMMONAPS 940 mg/g granules · PHEBURANE 483 mg/g granules · PHEBURANE 350 mg/mL oral solution
- Marketing authorisation holder
- Immedica Pharma AB, Eurocept International B. V.
- Information as of
- 2026-10-29
Key facts
Sodium phenylbutyrate (Ammonaps, Pheburane) binds nitrogen and allows its excretion. It is used as adjunctive therapy in the chronic management of urea cycle disorders.
What it is used for
- Adjunctive therapy in the chronic management of urea cycle disorders involving deficiencies of carbamylphosphate synthetase, ornithine transcarbamylase or argininosuccinate synthetase.
- All patients with neonatal-onset disease (within the first 28 days of life) and late-onset patients with a history of hyperammonaemic encephalopathy.
Dosing
- Daily dose adjusted to protein tolerance and dietary protein needs; usual dose 450 - 600 mg/kg/day in children weighing less than 20 kg and 9.9 - 13.0 g/m2/day in children over 20 kg, adolescents and adults.
- Safety of doses above 20 g/day has not been established (applies to Ammonaps and Pheburane).
- Ammonaps tablets only for patients able to swallow tablets; granules for infants, children and patients with dysphagia. Pheburane is available as granules and oral solution.
- Combine with dietary protein restriction, and in some cases essential amino acid and carnitine supplementation; citrulline or arginine supplementation depending on the enzyme defect; keep plasma glutamine below 1,000 µmol/l.
Contraindications
- Pregnancy and breast-feeding.
- Hypersensitivity to the active substance or any of the excipients.
Important warnings
- High sodium content (124 mg per gram of sodium phenylbutyrate; up to 2.5 g sodium at the maximum dose); caution in congestive heart failure, severe renal insufficiency and oedema.
- Monitor serum potassium (urinary potassium loss).
- Acute hyperammonaemic encephalopathy may occur even on therapy; not for managing acute hyperammonaemia.
- Ammonaps tablets should not be used in dysphagia (risk of oesophageal ulceration).
- Caution in hepatic or renal insufficiency.
Side effects
- Very common: amenorrhoea and irregular menstruation.
- Common: anaemia, thrombocytopenia, leukopenia, metabolic acidosis, alkalosis, decreased appetite, depression, irritability, syncope, headache, oedema, abdominal pain, vomiting, nausea, constipation, dysgeusia, rash, abnormal skin odour, renal tubular acidosis.
- Uncommon: aplastic anaemia, arrhythmia, pancreatitis, peptic ulcer.
Interactions
- Probenecid may affect renal excretion of the conjugation product.
- Haloperidol and valproate may induce hyperammonaemia; corticosteroids may raise plasma ammonia; monitor ammonia more often.
Pregnancy and breastfeeding
- Contraindicated during pregnancy and breast-feeding.
- Women of child-bearing potential must use effective contraception.
Summary of the official product information, written with AI on 2026-10-29. Every number was checked automatically against the original text. Not reviewed by a physician – the full official text is authoritative.
Common questions – ask Medelix
For patients
Package leaflet, verbatim
This product has no separate US patient information.
Authorisation and brand names by country
Medicines with exactly this active-substance composition, as listed in the national registers – alphabetical and without ranking. Whether a product is currently available is not shown here.
EU – centrally authorised (all member states)
Source: European Medicines Agency (EMA), product information
Brand names in 3 more European countries
- Iceland
- Ammonaps, Pheburane
- Liechtenstein
- Ammonaps
- Norway
- Ammonaps, Pheburane
EMA – Article 57 product data (EU/EEA), 2026-10-29
Medelix receives no money from pharmaceutical companies. Brand names are listed alphabetically and without ranking.
Other substances in the same group
Another question about this substance?
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Sources
- European Medicines Agency. Ammonaps – EPAR, Product Information. 2026-10-29. https://www.ema.europa.eu/en/documents/product-information/ammonaps-epar-product-information_en.pdf
- European Medicines Agency. Pheburane – EPAR, Product Information. 2026-10-29. https://www.ema.europa.eu/en/documents/product-information/pheburane-epar-product-information_en.pdf
Editorial: Medelix editorial team · last updated 2026-10-29 · How these pages are made · Report an error
Source: European Medicines Agency (EMA), product information. Not advertising, not a treatment recommendation. For questions about your own treatment, ask your doctor or pharmacist.