Bacitracin Zinc and Polymyxin B Sulfate Ointment
» Bacitracin Zinc and Polymyxin B Sulfate Ointment contains the equivalent of not less than 90.0 percent and not more than 130.0 percent of the labeled amounts of bacitracin and polymyxin B. It may contain a suitable local anesthetic.
Packaging and storage Preserve in well-closed, light-resistant containers.
Thin-layer chromatographic identification test 201BNP: meets the requirements.
Minimum fill 755: meets the requirements.
Water, Method I 921: not more than 0.5%, 20 mL of a mixture of toluene and methanol (7:3) being used in place of methanol in the titration vessel.
Assay for bacitracin Proceed with Ointment as directed in the Assay under Bacitracin Zinc Ointment.
Assay for polymyxin B Proceed as directed for polymyxin B under AntibioticsMicrobial Assays 81, using an accurately weighed portion of Ointment shaken with about 50 mL of ether in a separator, and extracted with four 20-mL portions of Buffer No. 6. Combine the aqueous extracts, and dilute with Buffer No. 6 to an appropriate volume to obtain a stock solution. Dilute this stock solution quantitatively and stepwise with Buffer No. 6 to obtain a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard.
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USP32NF27 Page 1624Pharmacopeial Forum: Volume No. 28(4) Page 1071