Cloxacillin Benzathine Intramammary Infusion
» Cloxacillin Benzathine Intramammary Infusion is a suspension of Cloxacillin Benzathine in a suitable oil vehicle. It has a potency equivalent to not less than 90.0 percent and not more than 120.0 percent of the labeled amount of cloxacillin (C19H18ClN3O5S).
Packaging and storage— Preserve in disposable syringes that are well-closed containers, except that where the Intramammary Infusion is labeled as sterile, the individual syringes or cartons are sealed and tamper-proof so that sterility is assured at time of use.
Labeling— Label it to indicate that it is for veterinary use only. Intramammary Infusion that is sterile may be so labeled.
USP Reference standards 11
USP Cloxacillin Benzathine RS Click to View Structure
USP Cloxacillin Sodium RS Click to View Structure
Identification, Infrared Absorption 197K Obtain the test specimen as follows. Transfer a quantity of Intramammary Infusion, equivalent to about 500 mg of cloxacillin, to a 50-mL centrifuge tube, add 25 mL of toluene, mix, and centrifuge. Decant and discard the toluene. Wash the residue with four 25-mL portions of toluene, sonicating for about 30 seconds after each addition of toluene. Dry the residue in vacuum over silica gel.
Sterility 71 (where labeled as being sterile)— It meets the requirements when tested as directed for Direct Inoculation of the Culture Medium under Test for Sterility of the Product to be Examined, except to use Fluid Thioglycollate Medium containing polysorbate 80 solution (1 in 200) and an amount of sterile penicillinase sufficient to inactivate the cloxacillin in each tube, to use Soybean–Casein Digest Medium containing polysorbate 80 solution (1 in 200) and an amount of sterile penicillinase sufficient to inactivate the cloxacillin in each tube, and to shake the tubes once daily.
Water, Method I 921: not more than 1.0%, 20 mL of a mixture of toluene and methanol (7:3) being used in place of methanol in the titration vessel.
0.1M Phosphate buffer, Mobile phase, Diluent, Standard preparations, and Chromatographic system— Proceed as directed in the Assay under Cloxacillin Benzathine.
Assay preparations— In duplicate, quantitatively express the entire contents of a syringe of Cloxacillin Benzathine Intramammary Infusion into a 500-mL volumetric flask. Add about 300 mL of methanol, and stir for 45 minutes ± 1 minute. Dilute with methanol to volume, and stir for an additional 10 minutes ± 1 minute. Immediately transfer 45 mL of the resulting solution to a 50-mL polypropylene centrifuge tube, and centrifuge for 10 minutes. From the supernatant remove an aliquot, and dilute with a sufficient volume of Diluent to prepare a solution containing about 100 µg of cloxacillin per mL.
Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparations and the Assay preparations into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity, in µg, of C19H18ClN3O5S in each syringe of Cloxacillin Benzathine Intramammary Infusion taken by the formula:
P(CD/1000)(rU / rS)
in which P is the assigned potency, in µg of cloxacillin per mg, of USP Cloxacillin Sodium RS; C is the concentration, in µg per mL, of cloxacillin sodium in the Standard preparations; D is the dilution factor used in preparing the Assay preparations; and rU and rS are the average peak areas of the cloxacillin peaks obtained from the Assay preparations and the Standard preparations, respectively.
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