Sodium Phenylbutyrate Compounded Oral Suspension

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Sodium Phenylbutyrate Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of sodium phenylbutyrate (C₁₀H₁₁Na).

Prepare Sodium Phenylbutyrate Compounded Oral Suspension 200 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 〈795〉).

^a Ucyclyd Pharma, Inc., Scottsdale, AZ.

^b Paddock Laboratories, Minneapolis, MN.

Calculate the required quantity of each ingredient for the total amount to be prepared. Place the Sodium Phenylbutyrate powder in a suitable mortar, and comminute to a fine powder with a pestle. Add the Vehicle in small portions, and triturate to make a smooth paste. Add increasing volumes of the Vehicle to make a sodium phenylbutyrate liquid that is pourable. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated bottle. Add enough of the Vehicle to bring to final volume, and mix well.

2 ASSAY

Procedure

Mobile phase: Acetonitrile and 5 mM phosphoric acid (40:60). Filter and degas.

Standard solution: 0.1 mg/mL of sodium phenylbutyrate in Mobile phase. [Note—The Standard solution should be prepared from the appropriate reference material.]

Sample solution: Shake thoroughly by hand each bottle of Oral Suspension. Prepare 0.1 mg/mL of sodium phenylbutyrate from Oral

Suspension and Mobile phase.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 218 nm

Column: 4.6-mm × 25-cm; 5-μm packing L1

Column temperature: 60°

Flow rate: 1.0 mL/min

Injection volume: 5 μL

System suitability

Sample: Standard solution

[Note—The retention time for sodium phenylbutyrate is about 3.0 min.]

Suitability requirements

Relative standard deviation: NMT 2.0% for replicate injections

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of sodium phenylbutyrate (C₁₀H₁₁Na) in the portion of Oral Suspension taken:

Result = (r_U/r_S ) × (C_S /C_U ) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of sodium phenylbutyrate in the Standard solution (mg/mL)

C_U = nominal concentration of sodium phenylbutyrate in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

pH 〈791〉: 7.0–8.0

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Package in tight, light-resistant containers. Store at controlled room temperature.

Beyond-Use Date: NMT 90 days after the date on which it was compounded when stored at controlled room temperature

Labeling: Label it to indicate that it is to be well shaken before use, and to state the Beyond-Use Date.