Baclofen 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

Baclofen Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of baclofen (C₁₀H₁₂ClNO₂).

Prepare Baclofen Compounded Oral Suspension 5 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 〈795〉).

Baclofen 500 mg

Vehicle: a 1:1 mixture of Vehicle for Oral Solution (regular or sugar-free), NF, and Vehicle for Oral Suspension, NF, a sufficient quantity to make 100 mL

If using Baclofen Tablets, place the Tablets in a suitable mortar and comminute to a fine powder, or add Baclofen powder. Add 5 mL of the Vehicle to wet the powder, and triturate the powder to form a fine paste. Add the Vehicle in small portions almost to volume, and mix thoroughly after each addition. Transfer, stepwise and quantitatively, the contents of the mortar to a calibrated bottle. Add sufficient Vehicle to bring to final volume, and mix well.

2 ASSAY

Procedure

Mobile phase: Acetonitrile and 0.05 M monobasic sodium phosphate (20:80). Adjust with phosphoric acid to a pH of 3.5.

Standard solution: 5 µg/mL of USP Baclofen RS in water

Sample solution: Shake thoroughly by hand each bottle of Oral Suspension. Pipet 0.5 mL of Oral Suspension from each bottle to a 500-mL volumetric flask, dilute with water to volume to obtain a concentration of 5 µg/mL, and pass through a 0.22-µm polyvinylidene fluoride (PVDF) filter.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 220 nm

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

Flow rate: 1 mL/min

Injection volume: 15 µL

System suitability

Sample: Standard solution

[Note—The retention time of baclofen is about 5.5 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 baclofen (C₁₀H₁₂ClNO₂) in the portion of Oral Suspension taken:

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × 100

rᵤ = peak response from the Sample solution

rₛ = peak response from the Standard solution

Cₛ = concentration of USP Baclofen RS in the Standard solution (µg/mL)

Cᵤ = nominal concentration of baclofen in the Sample solution (µg/mL)

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

pH 〈791〉: 4.2–5.2

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Package in tight, light-resistant containers. Store in a refrigerator.

Beyond-Use Date: NMT 35 days after the day on which it was compounded when stored in a refrigerator

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

USP Reference Standards 〈11〉

USP Baclofen RS