Cefoxitin 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 

Cefoxitin for Injection is a sterile solution of Cefoxitin Sodium and one or more suitable buffer substances in Water for Injection. It contains Dextrose or Sodium Chloride as a tonicity-adjusting agent. It contains the equivalent of NLT 90.0% and NMT 120.0% of the labeled amount of cefoxitin (C₁₆H₁₇N₃O₇S₂). 

2 IDENTIFICATION

A. 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 

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: 0.3 mg/mL of cefoxitin prepared as follows. Allow one container of Injection to thaw, and mix. Dilute an aliquot of Injection with Buffer to a suitable 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 the sample solution (mg/mL) 

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

Acceptance criteria: 90.0%–120.0% 

4 SPECIFIC TESTS 

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. 

pH 〈791〉 : 4.5-8.0

Particulate Matter in Injections 〈788〉: It meets the requirements for small-volume injections.

5 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve as described in Packaging and Storage Requirements 〈659〉, Injection Packaging, Maintain in the frozen state.

Labeling: It meets the requirements in Labeling 〈7〉, Labels and Labeling for Injectable Products. The label states that it is to be thawed just before use, describes conditions for proper storage of the resultant solution, and directs that the solution is not to be refrozen.

USP Reference Standards 〈11〉 

USP Cefoxitin RS