Cefoxitin for Injection

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

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

DOWNLOAD PDF HERE

1 DEFINITION 

Cefoxitin for Injection contains Cefoxitin Sodium equivalent to NLT 90.0% and NMT 120.0% of the labeled amount of cefoxitin (C₁₆H₁₇N₃O₇S₂). 

2 ASSAY 

Procedure 

Buffer: Dissolve 1.0 g of monobasic potassium phosphate and 1.8 g of dibasic sodium phosphate in 900 mL of water. Adjust with phosphoric acid or 10 N sodium hydroxide to a pH of 7.1 ± 0.1, and dilute with water to 1 L. Pass through a membrane filter of 1-µm or finer pore size.

Mobile phase: Acetonitrile, water, and glacial acetic acid (160:840:10). Pass through a membrane filter of 1-µm or finer pore size.

Standard solution: 0.3 mg/mL of USP Cefoxitin RS in Buffer. Sonicate, if necessary, to dissolve. Use this solution within 5 h. Sample solution 1 (where it is represented as being in a single-dose container): Nominally 0.3 mg/mL of cefoxitin prepared as follows. Constitute Cefoxitin for Injection in a volume of water corresponding to the volume of solvent specified in the labeling. Withdraw all of the withdrawable contents, using a suitable hypodermic needle and syringe, transfer to a suitable volumetric flask, and dilute with water to volume. Use this solution within 5 h. 

Sample solution 2 (where the label states the quantity of cefoxitin in a given volume of constituted solution): Nominally 0.3 mg/mL of cefoxitin prepared as follows. Constitute Cefoxitin for Injection in a volume of water corresponding to the volume of solvent specified in the labeling. Transfer a suitable aliquot of the constituted solution to a suitable volumetric flask, and dilute with water to volume. Use this solution within 5 h. 

Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 254 nm 

Column: 3.9-mm × 30-cm; 5- to 10-µm packing L1 

Flow rate: 1 mL/min 

Injection volume: 10 µL 

System suitability 

Sample: Standard solution 

Suitability requirements 

Column efficiency: NLT 2800 theoretical plates 

Tailing factor: NMT 1.5 

Relative standard deviation: NMT 1.0% 

Analysis 

Samples: Sample solution 1 or Sample solution 2 and Standard solution 

Calculate the percentage of the labeled amount of cefoxitin (C₁₆H₁₇N₃O₇S₂) in the portion of Cefoxitin for Injection taken: 

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

r_U = peak response from the Sample solution  

r_S = peak response from the Standard solution 

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

C_U = nominal concentration of cefoxitin in Sample solution 1 or Sample solution 2 (mg/mL) 

P = potency of cefoxitin in USP Cefoxitin RS (mg/mg) 

Acceptance criteria: 90.0%–120.0% 

3 PERFORMANCE TESTS 

Uniformity of Dosage Units 〈905〉: Meets the requirements 

4 SPECIFIC TESTS 

Constituted Solution: At the time of use, it meets the requirements in Injections and Implanted Drug Products 〈1〉, Specic Tests, Completeness and clarity of solutions. 

Bacterial Endotoxins Test 〈85〉: NMT 0.13 USP Endotoxin Unit/mg of cefoxitin 

Sterility Tests 〈71〉: It meets the requirements when tested as directed in Test for Sterility of the Product to Be Examined, Membrane Filtration. Particulate Matter in Injections 〈788〉: It meets the requirements for small-volume injections. 

pH 〈791〉 

Sample solution: 100 mg/mL 

Acceptance criteria: 4.2–7.0 

Water Determination, Method I〈921〉 

Analysis: Use a mixture of ethylene glycol and pyridine (3:1) in the titration vessel in place of methanol. 

Acceptance criteria: NMT 1.0% 

Other Requirements: It meets the requirements of the Identification tests in Cefoxitin Sodium. It meets the requirements in Labeling 〈7〉, Labels and Labeling for Injectable Products. 

5 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve as described in Packaging and Storage Requirements 〈659〉, Injection Packaging, Packaging for constitution. USP Reference Standards 〈11〉 

USP Cefoxitin RS