Mupirocin Ointment

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

Mupirocin Ointment contains NLT 90.0% and NMT 110.0% of the labeled amount of mupirocin (C₂₆H₄₄O₉).

2 IDENTIFICATION

A. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

B. The UV spectrum of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

PROCEDURE

Buffer: 6.0 g/L of sodium phosphate, monobasic. Adjust with 10 N sodium hydroxide TS to a pH of 6.3.

Mobile phase: Acetonitrile and Buffer (1:3)

Standard solution: 0.11 mg/mL of USP Mupirocin Lithium RS prepared as follows. Transfer a suitable amount of USP Mupirocin Lithium RS to an adequate volumetric flask, add 25% of the total volume of acetonitrile, and swirl to dissolve. Dilute with Buffer to volume.

System suitability solution: Adjust 10 mL of Standard solution with 6 N hydrochloric acid TS to a pH of 2.0, allow to stand for 2 h, and adjust with 5 N sodium hydroxide TS to a pH of 6.3.

Sample solution: Nominally 0.1 mg/mL of mupirocin from Ointment prepared as follows. Dissolve a quantity of Ointment, equivalent to 10 mg of mupirocin, in 25 ml. of acetonitrile. Transfer this solution, with the aid of Buffer, to a 100-ml volumetric flask, and dilute with Buffer to volume.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 229 nm. For Identification B, use a diode array detector in the range of 200-400 nm.

Column: 4.6-mm x 25-cm; 10-µm packing 11

Flow rate: 2 mL/min

Injection volume: 20 µL

System suitability

Samples: Standard solution and System suitability solution

Suitability requirements

Resolution: NLT 2.0 between mupirocin pyranyl analog and mupirocin, System suitability solution

[NOTE- Two hydrolysis products are formed, with the following elution order: mupirocin furonyl analog, mupirocin pyranyl analog, and mupirocin.]

Tailing factor: NMT 2, Standard solution

Relative standard deviation: NMT 2.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of mupirocin (C₂₆H₄₄O₉) in the portion of Ointment taken:

Result = (r_u /r_s ) × (C_s /C_u ) × P × F × 100

r_u = peak response of mupirocin from the Sample solution

r_s = peak response of mupirocin from the Standard solution

C_s = concentration of USP Mupirocin Lithium RS in the Standard solution (mg/mL)

C_u = nominal concentration of mupirocin in the Sample solution (mg/mL)

P = potency of mupirocin in USP Mupirocin Lithium RS (µg/mg)

F = conversion factor, 0.001 mg/µg

Acceptance criteria: 90.0%–110.0%

4 IMPURITIES

Change to read:

Organic Impurities

Solution A: 10.5 g/L of ammonium acetate. Adjust with acetic acid, glacial to a pH of 5.7.

Solution B: Tetrahydrofuran and water (1:1)

Solution C: 13.6 g/L of sodium acetate, anhydrous. Adjust with acetic acid, glacial to a pH of 4.0.

Mobile phase: See Table 1.

Table 1

Diluent: Methanol and Solution C (1:1)

System suitability solution: 0.1 mg/mL of USP Mupirocin Lithium RS in Diluent. Adjust with 6 N Hydrochloric Acid TS to a pH of 2.0 and allow to stand for 2 h.

Sensitivity solution: 0.002 mg/mL of mupirocin from USP Mupirocin Lithium RS in Diluent

Standard solution: 0.025 mg/mL of mupirocin from USP Mupirocin Lithium RS in Diluent

Sample solution: Nominally 5 mg/mL of mupirocin in Diluent, prepared as follows. Accurately weigh 5.0 g of Ointment (equivalent to about 100 mg of mupirocin) and transfer it to a 50-mL glass centrifuge test tube. Add 20.0 mL of Diluent and sonicate in ice cold water for 5 min to dissolve. Pass through a suitable filter prior to use. Use freshly prepared solution.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 240 nm

Column: 4.6-mm x 25-cm, 5-µm packing 11

Column temperature: 30°

Flow rate: 1.0 mL/min

Injection volume: 20 µL

System suitability

Samples: System suitability solution, Sensitivity solution, and Standard solution

Suitability requirements

Resolution: NLT 7.0 between mupirocin pyranyl analog and mupirocin, System suitability solution

Relative standard deviation: NMT 5.0%, Standard solution

Signal-to-noise ratio: NLT 10, Sensitivity solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each impurity in the portion of Ointment taken:

Result = (r_u /r_s ) × (C_s /C_u ) × P × F × 100

r_u = peak area of any impurity from the Sample solution

r_s = peak area of mupirocin from the Standard solution

C_s = concentration of USP Mupirocin Lithium RS in the Standard solution (mg/mL)

C_u = nominal concentration of mupirocin in the Sample solution (mg/mL)

P = potency of mupirocin in USP Mupirocin Lithium RS (µg/mg)

F = conversion factor, 0.001 mg/µg

Acceptance criteria: See Table 2. The reporting threshold is 0.04%.

Table 2

^a 7-{(E)-4-[(2S,3R,4R,5S)-3,4-Dihydroxy-5-({(2S,3S)-3-[(2S,3S)-3-hydroxybutan-2-yl]oxiran-2-yl}methyl)tetrahydro-2H-pyran-2-yl]-3-methylbut-2-enoyloxy}heptanoic acid.

^b 9-{(E)-4-[(2R,3aS,6S,7S)-2-{(1RS,2S,3S)-1,3-Dihydroxy-2-methylbutyl}-7-hydroxyhexahydro-2H-furo[3,2-c]pyran-6-yl]-3-methylbut-2-enoyloxy}nonanoic acid. _{(ERR 1-May-2022)}

^c 9-{(E)-4-[(2R,3RS,4aS,7S,8S,8aR)-3,8-Dihydroxy-2-{(2S,3S)-3-hydroxybutan-2-yl}octahydropyrano[3,2-c]pyran-7-yl]-3-methylbut-2-enoyloxy}nonanoic acid.

^d (E)-9-{(E)-4-[(2S,3R,4R,5S)-3,4-Dihydroxy-5-({(2S,3S)-3-[(2S,3S)-3-hydroxybutan-2-yl]oxiran-2-yl}methyl)tetrahydro-2H-pyran-2-yl]-3-methylbut-2-enoyloxy}non-4-enoic acid.

^e 9-{(E)-3-Methyl-4-[(2S,3R,4S,5R)-3,4,5-trihydroxy-5-({(2S,3S)-3-[(2S,3S)-3-hydroxybutan-2-yl]oxiran-2-yl}methyl)tetrahydro-2H-pyran-2-yl]but2-enoyloxy}nonanoic acid.

^f 9-((E)-4-{(2S,3R,4R,5S)-3,4-Dihydroxy-5-[(4R,5S,E)-5-hydroxy-4-methylhex-2-enyl]tetrahydro-2H-pyran-2-yl}-3-methylbut-2-enoyloxy)nonanoic acid.

5 PERFORMANCE TESTS

MINIMUM FILL (755): Meets the requirements

6 SPECIFIC TESTS

MICROBIAL ENUMERATION TESTS (61), and TESTS FOR SPECIFIED MICROORGANISMS (62): The total aerobic microbial count does not exceed 102 cfu/g. The

total combined molds and yeasts count does not exceed 10 cfu/g. It meets the requirements of the tests for the absence of Staphylococcus aureus and Pseudomonas aeruginosa.

7 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in collapsible tubes or well-closed containers. Store at controlled room temperature,

USP REFERENCE STANDARDS (11)

USP Mupirocin Lithium RS

Lithium 9-((E)-4-[(2S,3R,4R,5S)-3,4-dihydroxy-5-({(2S,3S)-3-[(2S,3S)-3-hydroxybutan-2-yl)oxiran-2-yl)methyl)tetrahydro-2H-pyran-2-yl]-3-

methylbut-2-enoyloxy}nonanoate.

C₂₆H₄₃LiO₉        506.56