Baclofen

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 contains NLT 98.0% and NMT 102.0% of baclofen (C₁₀H₁₂ClNO₂), calculated on the anhydrous basis.

2 IDENTIFICATION

Change to read:
A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197M
B. The retention time of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

Procedure
Solution A: Dissolve 1.38 g of potassium dihydrogen phosphate and 1.74 g of sodium-1-pentanesulfonate in 1 L of water. Adjust with dilute phosphoric acid to a pH of 3.0.
Solution B: Acetonitrile and methanol (1:1)
Diluent: Solution A and Solution B (65:35)
Mobile phase: See Table 1.

Standard solution: 0.2 mg/mL of USP Baclofen RS in Diluent

Sample solution: 0.2 mg/mL of Baclofen in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 225 nm

Column: 4.6-mm × 25.0-cm; 5-µm packing L1

Column temperature: 35°

Flow rate: 0.8 mL/min

Injection volume: 10 µL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 1.5

Relative standard deviation: NMT 1.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of baclofen (C₁₀H₁₂ClNO₂) in the portion of the Baclofen 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 (mg/mL)

Cᵤ = concentration of Baclofen in the Sample solution (mg/mL)

Acceptance criteria: 98.0%–102.0% on the anhydrous basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.3%

Organic Impurities

Solution A, Solution B, Diluent, Mobile phase, and Chromatographic system: Proceed as directed in the Assay.

Standard solution: 0.0015 mg/mL of USP Baclofen RS and 0.003 mg/mL of USP Baclofen Related Compound A RS in Diluent

Sample solution: 0.3 mg/mL of Baclofen in Diluent

System suitability

Sample: Standard solution

[Note—See Table 2 for relative retention times.]

Suitability requirements

Tailing factor: NMT 1.5 for baclofen

Relative standard deviation: NMT 5.0% for both baclofen and baclofen related compound A

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of baclofen related compound A in the portion of the Baclofen 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 (mg/mL)

Cᵤ = concentration of Baclofen in the Sample solution (mg/mL)

Calculate the percentage of any unspecified impurity in the portion of the Baclofen taken:

Result = (rᵢ/r_b) × (Cₛ/Cᵤ) × 100

rᵢ = peak response of any unspecified 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 (mg/mL)

Cᵤ = concentration of Baclofen in the Sample solution (mg/mL)

Acceptance criteria: See Table 2.

5 SPECIFIC TESTS

Water Determination, Method I 〈921〉: NMT 3.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers. Store at room temperature.

USP Reference Standards 〈11〉

USP Baclofen RS

USP Baclofen Related Compound A RS

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

C₁₀H₁₀ClNO 195.65