Carprofen

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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C₁₅H₁₂ClNO₂ 273.71

9H-Carbazole-2-acetic acid, 6-chloro-α-methyl-, (±)-;

(±)-6-Chloro-α-methylcarbazole-2-acetic acid CAS RN®: 53716-49-7; UNII: FFL0D546HO.

1 DEFINITION

Carprofen contains NLT 98.0% and NMT 102.0% of carprofen (C₁₅H₁₂ClNO₂), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020) : [Note—Methods described in 〈197K〉 or 〈197A〉 may

be used. If the spectra obtained in the solid state show differences, dissolve the substance to be examined and the reference substance

separately in acetone, evaporate to dryness, and record new spectra using the residues.]

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

3 ASSAY

3.1 Procedure

[Note—Protect all solutions containing carprofen from light.]

Mobile phase: Acetonitrile, methanol, glacial acetic acid, and water (40:25:0.2:35)

System suitability stock solution: 16 μg/mL of USP Carprofen Related Compound A RS in Mobile phase. Sonicate if necessary.

Standard solution: 160 μg/mL of USP Carprofen RS in Mobile phase. Sonicate if necessary.

System suitability solution: 1.6 μg/mL of USP Carprofen Related Compound A RS and 16 μg/mL of USP Carprofen RS in Mobile phase

prepared as follows. Mix 10 mL of System suitability stock solution and 10 mL of the Standard solution and dilute with Mobile phase to 100mL.

Sample solution: 160 μg/mL of Carprofen in Mobile phase

3.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 239 nm

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

Flow rate: 1 mL/min

Injection volume: 10 μL

3.3 System suitability

Sample: System suitability solution

3.4 Suitability requirements

Resolution: NLT 2.0 between carprofen and carprofen related compound A

Tailing factor: NMT 2.0 for the carprofen peak

Relative standard deviation: NMT 2.0% for the carprofen peak

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of carprofen (C₁₅H₁₂ClNO₂) in the portion of Carprofen taken:

Result = (r_U/r_S) x (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 USP Carprofen RS in the Standard solution (μg/mL)

C_U = concentration of Carprofen in the Sample solution (μg/mL)

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

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.1%

Organic Impurities

Mobile phase, System suitability solution, Sample solution, Chromatographic system, and System suitability: Proceed as directed in the

Assay.

Analysis

Sample: Sample solution

Calculate the percentage of each impurity in the portion of Carprofen taken:

Result = (r_U/r_T) × 100

r_U = peak response of each individual peak (other than the major peak of carprofen)

r_T = sum of all the peak responses

Acceptance criteria: See Table 1.

Table 1

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry at 105° for 2 h.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers. Store at 25°, excursions permitted between 15° and 30°.

Labeling: Label it to indicate that it is intended for veterinary use only.

USP Reference Standards 〈11〉

USP Carprofen RS

USP Carprofen Related Compound A RS

Carbazole.

C₁₂H₉NO 167.21