• Inborn errors of metabolism

Olpruva Generic Name & Formulations

General Description

Sodium phenylbutyrate 2g, 3g, 4g, 5g, 6g, 6.67g; pellets for oral susp after reconstitution; contains sodium 124mg/g.

Pharmacological Class

Nitrogen-binding agent.

How Supplied

Kit—1 (pellets + suspending agent)


Generic Availability


Mechanism of Action

Sodium phenylbutyrate is a pro-drug and is metabolized to phenylacetate. Phenylacetate is a metabolically active compound that conjugates with glutamine via acetylation to form phenylacetylglutamine. Phenylacetylglutamine is excreted by the kidneys, hence providing an alternate vehicle for waste nitrogen excretion.

Olpruva Indications


Adjunct in the chronic management of urea cycle disorders involving deficiencies of carbamylphosphate synthetase, ornithine transcarbamylase, or argininosuccinic acid synthetase.

Limitations of Use

Not for treatment of acute hyperammonemia. 

Olpruva Dosage and Administration

Adults and Children

See full labeling. Take with food; drink entire susp within 5mins after stirring. Do not give via gastrostomy or NG tubes. ≥20kg and BSA ≥1.2m2: 9.9–13g/m2/day in 3–6 doses; max 20g/day. Use in combination with dietary protein restriction and/or amino acid supplementation (eg, essential amino acids, arginine, citrulline, protein-free calorie supplements). Hepatic impairment, elderly: start at the lower end of dosing range. 

Olpruva Contraindications

Not Applicable

Olpruva Boxed Warnings

Not Applicable

Olpruva Warnings/Precautions


Risk for neurotoxicity (phenylacetate metabolite exposure). Obtain plasma levels of phenylacetate and phenylacetylglutamine. Consider reducing dose if neurologic symptoms (eg, vomiting, nausea, headache, somnolence, confusion) occur in absence of high ammonia levels or other incurrent illness. Monitor serum potassium; initiate treatment when necessary. Conditions associated with edema (eg, heart failure, cirrhosis, nephrosis): consider sodium content. Discontinue if new-onset edema develops or worsening edema during treatment. Renal impairment: monitor plasma ammonia levels at initiation. Hepatic impairment. Elderly. Pregnancy. Nursing mothers. 

Olpruva Pharmacokinetics


Apparent volume of distribution of phenylbutyrate: 7.2 L (under fasted conditions). 




Renal. Half-life: 0.5 hours (phenylbutyrate); 1.2 hours (phenylacetate). 

Olpruva Interactions


May be potentiated by probenecid. Corticosteroids may increase plasma ammonia levels. Hyperammonemia possible with haloperidol and valproic acid.

Olpruva Adverse Reactions

Adverse Reactions

Menstrual dysfunction, decreased appetite, body odor, bad taste, taste aversion; neurotoxicity. 

Olpruva Clinical Trials

See Literature

Olpruva Note

Not Applicable

Olpruva Patient Counseling

See Literature