Polymyxin B Sulfate and Bacitracin Zinc Topical Powder
» Polymyxin B Sulfate and Bacitracin Zinc Topical Powder contains not less than 90.0 percent and not more than 130.0 percent of the labeled amounts of polymyxin B and bacitracin.
Packaging and storage Preserve in well-closed containers.
USP Reference standards 11
USP Bacitracin Zinc RS
USP Polymyxin B Sulfate RS
Microbial enumeration tests 61 and Tests for specified microorganisms 62 Collect aseptically in a suitable container about 1 g from not less than 5 containers, dissolve in 500 mL of Fluid A, filter through a membrane filter as directed for Membrane Filtration under Test for Sterility of the Product to be Examined under Sterility Tests 71, except to place the filter on the surface of SoybeanCasein Digest Agar Medium in a Petri dish, incubate for 7 days at 30 to 35, and count the number of colonies on the filter. Similarly prepare a second specimen, except to incubate at 20 to 25. Not more than 20 colonies are observed from the two specimens. It meets also the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa under Microbial Enumeration Tests 61 and Tests for specified microorganisms 62.
Water, Method I 921: not more than 7.0%.
Assay for polymyxin B Proceed as directed for polymyxin B under AntibioticsMicrobial Assays 81, using an accurately weighed portion of Topical Powder, equivalent to about 5000 USP Polymyxin B Units, shaken with 20 mL of water in a suitable volumetric flask. Dilute with Buffer No. 6 to volume, and mix. Dilute an accurately measured volume of the solution so obtained quantitatively with Buffer No. 6 to obtain a Test Dilution having a concentration of polymyxin B assumed to be equal to the median dose level of the Standard.
Assay for bacitracin Proceed as directed for bacitracin under AntibioticsMicrobial Assays 81, using an accurately weighed portion of Topical Powder, equivalent to about 800 USP Bacitracin Units, added to a 100-mL volumetric flask, dilute with 0.01 N hydrochloric acid to volume, and mix. Dilute this solution quantitatively with Buffer No. 1 to obtain a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard. In preparing each test dilution of the Standard, add additional hydrochloric acid to each to obtain the same concentration of hydrochloric acid as in the Test Dilution.
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USP35NF30 Page 4350