Baclofen Injection

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 Injection is a sterile solution of Baclofen in Water for Injection. It contains NLT 95.0% and NMT 105.0% of the labeled amount of baclofen (C₁₀H₁₂ClNO₂).

2 IDENTIFICATION

A. The retention time of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

B. The UV spectrum of baclofen in the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

Procedure

Mobile phase: 5.0 g/L of sodium dodecyl sulfate prepared as follows. Transfer a suitable portion of sodium dodecyl sulfate to an appropriate volumetric flask. Add 50% of the flask volume of water and then 0.5% of the flask volume of phosphoric acid. Add 40% of the flask volume of acetonitrile. Dilute with water to volume.

System suitability stock solution 1: 200 µg/mL of USP Baclofen Related Compound A RS prepared as follows. Transfer a suitable portion of USP Baclofen Related Compound A RS to an appropriate volumetric flask. Dissolve in 10% of the flask volume of acetonitrile. Dilute with water to volume.

System suitability stock solution 2: 20 µg/mL of USP Baclofen Related Compound A RS from System suitability stock solution 1, in water

Standard stock solution: 500 µg/mL of USP Baclofen RS in water

System suitability solution: 0.5 µg/mL of USP Baclofen Related Compound A RS from System suitability stock solution 2 and 50 µg/mL of USP Baclofen RS from Standard stock solution in water

Standard solution: 50 µg/mL of USP Baclofen RS in water

Sample solution: Nominally 50 µg/mL of baclofen from Injection. Use a portion of Injection. Dilute with water, if necessary.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 218 nm. For Identification B, use a diode array detector in the range of 210–400 nm.

Column: 4.6-mm × 25-cm; 10-µm packing L1

Flow rate: 1.5 mL/min

Injection volume: 50 µL

Run time: NLT 1.6 times the retention time of baclofen

System suitability

Samples: System suitability solution and Standard solution

[Note—See Table 1 for the relative retention times.]

Suitability requirements

Resolution: NLT 4.0 between baclofen related compound A and baclofen, System suitability solution

Tailing factor: NMT 1.5 for baclofen, System suitability solution

Relative standard deviation: NMT 1.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of baclofen (C₁₀H₁₂ClNO₂) in the portion of Injection 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: 95.0%–105.0%

4 IMPURITIES

Organic Impurities

Mobile phase, System suitability stock solution 1, System suitability stock solution 2, Standard stock solution, System suitability solution, Sample solution, and Chromatographic system: Proceed as directed in the Assay.

Sensitivity solution: 0.05 µg/mL of USP Baclofen RS in water

Standard solution: 0.5 µg/mL of USP Baclofen Related Compound A RS from System suitability stock solution 2 and 0.25 µg/mL of USP Baclofen RS from Standard stock solution in water

System suitability

Samples: System suitability solution, Sensitivity solution, and Standard solution

[Note—See Table 1 for the relative retention times.]

Suitability requirements

Resolution: NLT 4.0 between baclofen related compound A and baclofen, System suitability solution

Relative standard deviation: NMT 5.0% each for baclofen related compound A and baclofen, Standard solution

Signal-to-noise ratio: NLT 10, Sensitivity solution

Analysis

Samples: Sample solution and Standard solution

Calculate the percentage of baclofen related compound A in the portion of Injection taken:

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × 100

rᵤ = peak response of baclofen related compound A from the Sample solution

rₛ = peak response of baclofen related compound A from the Standard solution

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

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

Calculate the percentage of any other impurity in the portion of Injection taken:

Result = (rᵢ/r_b) × (Cₛ/Cᵤ) × 100

rᵢ = peak response of any other impurity from the Sample solution

r_b = peak response of baclofen 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: See Table 1. The reporting threshold is 0.1%.

5 SPECIFIC TESTS

pH 〈791〉: 5.0–7.5

Particulate Matter in Injections 〈788〉: Meets the requirements for small-volume injections

Sterility Tests 〈71〉: Meets the requirements

Change to read:

Osmolality and Osmolarity 〈785〉

Osmolality: 270–320 mOsm/kg▲ (ERR 1-Aug-2022)

Bacterial Endotoxins Test 〈85〉: Meets the requirements

Other Requirements: Meets the requirements in Injections and Implanted Drug Products 〈1〉

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers. Do not freeze. Store at controlled room temperature.

USP Reference Standards 〈11〉

USP Baclofen RS

USP Baclofen Related Compound A RS

4-(4-Chlorophenyl)-2-pyrrolidinone.

C₁₀H₁₀ClNO 195.65