Cephradine
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
C16H19N3O4S 349.40
5-Thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 7-[(amino-1,4-cyclohexadien-1-ylacetyl)amino]-3-methyl-8-oxo-, [6R-[6α,7β(R*)]]-. (6R,7R)-7-[(R)-2-Amino-2-(1,4-cyclohexadien-1-yl)acetamido]-3- methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid CAS RN®: 38821-53-3.
Monohydrate 367.43 CAS RN®: 31828-50-9 (non-stoichiometric hydrate).
Dihydrate 385.44 CAS RN®: 58456-86-3.
Cephradine has a potency of not less than 900 µg and not more than 1050 µg of total cephalosporins per mg, calculated as the sum of cephradine (C16H19N3O4S) and Cephalexin (C16H19N3O4S), calculated on the anhydrous basis.
Packaging and storage—Preserve in tight containers.
Labeling—Where it is the dihydrate form, the label so indicates. Where the quantity of cephradine is indicated in the labeling of any preparation containing Cephradine, this shall be understood to be in terms of anhydrous cephradine (C16H19N3O4S). Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.
USP Reference standards 〈11〉
USP Cephradine RS
USP Cephalexin RS
Change to read:
Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K.
Crystallinity 〈695〉: meets the requirements.
pH 〈791〉: between 3.5 and 6.0, in a solution containing 10 mg per mL.
Water Determination, Method I 〈921〉: not more than 6.0%, except that if it is the dihydrate form, the limit is between 8.5% and 10.5%. Limit of cephalexin—Using the chromatogram of the Assay preparation obtained in the Assay, calculate the percentage of cephalexin (C16H19N3O4S) in the portion of Cephradine taken by the formula:
100(rUx/rU)
in which rUx is the cephalexin peak response in the chromatogram obtained from the Assay preparation, and rU is the sum of the cephalexin and cephradine peak responses in the chromatogram obtained from the Assay preparation: not more than 5.0%, calculated on the anhydrous basis, is found.
Other requirements—Where the label states that Cephradine is sterile, it meets the requirements for Sterility and Bacterial endotoxins under Cephradine for Injection. Where the label states that Cephradine must be subjected to further processing during the preparation of injectable dosage forms, it meets the requirements for Bacterial endotoxins under Cephradine for Injection.
Assay
Mobile phase—Prepare a mixture of water, methanol, 0.5 M sodium acetate, and 0.7 N acetic acid (782:200:15:3). Make adjustments if necessary (see System Suitability under Chromatography 〈621〉). Filter the solution through a filter of 1 µm or finer porosity, and degas before use.
Standard preparation—Dissolve an accurately weighed quantity of USP Cephradine RS quantitatively in Mobile phase to obtain a solution having a known concentration of about 0.5 mg per mL.
Resolution solution—Prepare a solution in Mobile phase containing in each mL about 0.5 mg of USP Cephradine RS and 0.5 mg of USP Cephalexin RS.
Assay preparation—Transfer about 50 mg of Cephradine, accurately weighed, to a 100-mL volumetric ask, add about 30 mL of Mobile phase, and sonicate. Dilute with Mobile phase to volume, and mix.
