U.S. PHARMACOPEIA

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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.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
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 Antibiotics—Microbial 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.
Auxiliary Information— Staff Liaison : Brian D. Gilbert, Ph.D., Scientist
Expert Committee : (MDANT05) Monograph Development-Antibiotics
USP29–NF24 Page 236
Pharmacopeial Forum : Volume No. 28(4) Page 1071
Phone Number : 1-301-816-8223