Bacitracin and Polymyxin B Sulfate Topical Aerosol

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Bacitracin and Polymyxin B Sulfate Topical Aerosol is a suspension of Bacitracin and Polymyxin B Sulfate in a suitable vehicle, packaged in a pressurized container with a suitable inert propellant. It contains NLT 90.0% and NMT 130.0% of the labeled amounts of bacitracin and polymyxin B. It may contain a suitable local anesthetic.

Prepare the specimen for the following tests and assays as follows. Maintain the container in the inverted position throughout this procedure. Store the container in a freezer at-70° for 16-24 h. Remove the container from the freezer, promptly puncture the container, and allow the propellant to volatilize. Open the container, and mix the contents.

2 IDENTIFICATION

A. THIN-LAYER CHROMATOGRAPHIC IDENTIFICATION TEST (201BNP).

Sample: Prepare as directed above.

Analysis: Test as directed in the section For Creams, Lotions, and Ointments in the chapter.

Acceptance criteria: Meets the requirements

3 ASSAY

3.1 BACITRACIN

(See Antibiotics-Microbial Assays (81).)

Sample solution: Use a portion of the contents of one container, containing nominally 500 USP Bacitracin Units, prepared as directed above. Transfer to a suitable separator containing 50 mL of ether, and extract with three 25-ml portions of Buffer B.1 (see the chapter). Combine the buffer extracts in a 100-ml volumetric flask, dilute with Buffer B.1 to volume, and mix.

Analysis: Proceed as directed in the chapter. Add sufficient 0.01 N hydrochloric acid to this solution so that the amount of hydrochloric acid in the Test Dilution is the same as in the median level of the standard. Dilute with Buffer B.1 to obtain a Test Dilution having a bacitracin concentration that is nominally equivalent to the median level of the standard.

Acceptance criteria: 90.0%-130.0%

3.2 POLYMYXIN B

(See Antibiotics-Microbial Assays (81).)

Sample solution: Use a portion of the contents of one container, containing nominally 5000 USP Polymyxin B Units, prepared as directed above. Transfer to a suitable separator containing 50 mL of ether, and extract with three 25-mL portions of Buffer B.6 (see the chapter). Combine the buffer extracts in a 100-mL volumetric flask, dilute with Buffer B.6 to volume, and mix.

Analysis: Proceed as directed in the chapter. Dilute a suitable aliquot of the Sample solution with Buffer B.6 to obtain a Test Dilution having a polymyxin B concentration that is nominally equivalent to the median level of the standard.

Acceptance criteria: 90.0%-130.0%

4 SPECIFIC TESTS

WATER DETERMINATION, Method / (921)

Analysis: Use a portion of the contents of one container, prepared as directed above, and 20 mL of a mixture of toluene and methanol (7:3) in place of methanol in the titration vessel.

Acceptance criteria: NMT 0.5%

OTHER REQUIREMENTS: It meets the requirements for Topical Aerosols (603), in the sections Pressure Test, Minimum Fill, and Leakage Test.

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in pressurized containers, and avoid exposure to excessive heat.

USP REFERENCE STANDARDS (11)

USP Bacitracin Zinc RS

USP Polymyxin B Sulfate RS