Cephapirin Benzathine
5-Thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 3-[(acetyl-oxy)methyl]-8-oxo-7-[[(4-pyridinylthio)acetyl]amino]-, (6R-trans)-, compd. with N,N¢-bis(phenylmethyl)-1,2-ethanediamine (2:1). (6R,7R)-3-(hydroxymethyl)-8-oxo-7-[2-(4-pyridylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid compound with N,N¢-dibenzylethylenediamine (2:1) ![]() ![]() ![]() » Cephapirin Benzathine contains the equivalent of not less than 715 µg and not more than 820 µg of cephapirin (C17H17N3O6S2) per mg.
Packaging and storage
Preserve in well-closed containers.
Labeling
Label it to indicate that it is for veterinary use only.
Crystallinity
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pH
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Water, Method I
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Benzathine content
Using about 1 g of Cephapirin Benzathine, accurately weighed, proceed as directed in the test for Benzathine content under Penicillin G Benzathine: between 20.0% and 24.0% of benzathine (C16H20N2), calculated on the anhydrous basis, is found.
Assay
Solution A
Transfer about 26.2 mL of acetic acid and about 99.12 g of potassium acetate to a 4-L volumetric flask. Add 2000 mL of water, and mix to dissolve. Dilute with water to volume, and pass through a 0.45-µm nylon filter.
Solution B
Use acetonitrile.
Mobile phase
Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments, if necessary (see System Suitability under Chromatography
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Extraction solution:
a mixture of 400 mL of acetic acid and 600 mL of water.
Dilution buffer
Dissolve about 205 g of potassium acetate in about 800 mL of water. Adjust with acetic acid to a pH of 7.5 to 8.2. Dilute with water to 1000 mL, and pass through a 0.45-µm nylon filter.
10% Acetic acid solution
Add about 10.0 mL of acetic acid to a 100-mL volumetric flask. Mix, and dilute with water to volume.
System suitability solution
Dissolve an accurately weighed quantity of USP Cephapirin Sodium RS in 10% Acetic acid solution to prepare a solution containing a known concentration of about 2.0 mg per mL. Heat the solution at 50
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Standard preparation
In duplicate, accurately weigh about 50 mg of USP Cephapirin Sodium RS, and transfer into a 25-mL volumetric flask. Add about 2.5 mL of Extraction solution and about 15.0 mL of Dilution buffer, and agitate to dissolve. Add 7.0 mL of acetonitrile, and mix well. Allow the solution to return to room temperature, and dilute with water to volume.
Assay preparation
In duplicate, weigh about 60 mg of Cephapirin Benzathine, and transfer into a 25-mL volumetric flask. Add about 2.5 mL of Extraction solution and 15.0 mL of Dilution buffer, and mix to dissolve. Add 7.0 mL of acetonitrile, and mix. Allow the flask to return to room temperature, and dilute with water to volume.
Chromatographic system (see Chromatography
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100(rV / ri)
in which rV is the height of the valley between cephapirin and any impurity; and ri is the impurity peak height. The percentage of the height of the valley is not more than 25% for the impurity peaks adjacent to the cephapirin peak. [noteThe System suitability solution is acceptable as long as the cephapirin peak is larger than the two peaks on either side of the cephapirin peak.] The relative standard deviation for replicate injections of the Standard preparation is not more than 3.0%.
Procedure
Separately inject equal volumes (about 2 µL) of the duplicate Standard preparation and the duplicate Assay preparation into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity, in µg, of C17H17N3O6S2 in each mg of Cephapirin Benzathine taken by the formula:
P(WS / WU)(VU / VS)(rU / rS)
in which P is the assigned potency, in µg of cephapirin per mg, of USP Cephapirin Sodium RS; WS and WU are the quantities of USP Cephapirin Sodium RS and Cephapirin Benzathine, in mg, used to prepare the Standard preparation and the Assay preparation, respectively; VS and VU are the final volumes, in mL, of the Standard preparation and the Assay preparation, respectively; and rU and rS are the average peak areas of the cephapirin peaks obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information
Please check for your question in the FAQs before contacting USP.
USP32NF27 Page 1875
Pharmacopeial Forum: Volume No. 30(2) Page 468
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