Mupirocin Cream
» Mupirocin Cream contains a quantity of Mupirocin Calcium equivalent to not less than 90.0 percent and not more than 120.0 percent of the labeled amount of mupirocin (C26H44O9). It may contain one or more suitable buffers, dispersants, and preservatives.
Packaging and storage— Preserve in collapsible tubes or well-closed containers. Store at 25, excursions permitted between 15 and 30.
Labeling— Label it to indicate that it contains Mupirocin Calcium and its equivalent content of mupirocin.
USP Reference standards 11—
USP Mupirocin Lithium RS
Identification— The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.
Minimum fill 755: meets the requirements.
pH 791: between 6.0 and 8.0.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 —It meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa. The total aerobic microbial count does not exceed 100 cfu per g.
Related compounds—
0.1 M Ammonium acetate, Solution A, Solution B, Mobile phase, and pH 6.3 Phosphate buffer— Proceed as directed in the Assay.
Sodium acetate solution— Add 5.8 mL of glacial acetic acid to 900 mL of water, adjust with sodium hydroxide TS to a pH of 4.0, dilute with water to 1000 mL, and mix.
Tetrahydrofuran solution— Mix 750 mL of tetrahydrofuran and 250 mL of water.
Sodium acetate and tetrahydrofuran solution— Prepare a mixture of Sodium acetate solution and Tetrahydrofuran solution (50:50).
System suitability solution— Use the Standard preparation, prepared as directed in the Assay.
Test stock solution —Transfer an accurately weighed quantity of Cream, equivalent to about 50 mg of mupirocin, to a screw-capped centrifuge tube. Add 5.0 mL of Tetrahydrofuran solution, cap, and disperse the Cream by mixing on a vortex mixer and shaking. Add 5.0 mL of Sodium acetate solution, cap, and mix. Centrifuge for about 15 minutes. Withdraw the lower layer from the tube, pass it through a filter having a 0.5-µm or finer porosity, and use the filtrate.
Test solution— Transfer 1.0 mL of the Test stock solution to a 50-mL volumetric flask, dilute with Sodium acetate and tetrahydrofuran solution to volume, mix, and pass through a filter having a 0.5-µm or finer porosity.
Chromatographic system (see Chromatography 621)— Prepare as directed in the Assay. Chromatograph the Test stock solution, and record the responses as directed for Procedure. Identify the peaks based on the relative retention times for mupirocin and related substances shown in Table 1: the resolution, R, between pseudomonic acid D and mupirocin is not less than 3. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the column efficiency for the mupirocin peak is not less than 7000 theoretical plates; the tailing factor for the mupirocin peak is not more than 1.75; and the relative standard deviation of the mupirocin peak for replicate injections is not more than 2%.
Procedure— [note—Ensure that buffers, dispersants, or preservatives in the formulation do not interfere with quantification of either impurities or degradation products. ] Separately inject equal volumes (about 20 µL) of the Test stock solution and the Test solution into the chromatograph, and measure the peak responses for all of the peaks that do not correspond to buffers, dispersants, or preservatives. Calculate the percentage of each related compound and degradation product relative to mupirocin in the portion of Cream taken by the formula:
(ri / rM)(100 / 50)
in which ri is the peak response for each related compound or degradation product obtained from the Test stock solution; rM is the peak response of the mupirocin peak obtained from the Test solution; and 50 is the dilution factor for the Test solution.
Table 1
Name Relative
Retention
Time		 Limit
(%)
Pseudomonic acid F1 0.36 NMT 1.2
Mupirocin impurity 12 0.6 NMT 8.5
Mupirocin impurity 23 0.63 NMT 16
Pseudomonic acid D4 0.75 NMT 3.0
Pseudomonic acid B5 0.9 NMT 1.2
Mupirocin 1.0 —
Mupirocin impurity 36 1.15 NMT 1.2
Mupirocin impurity 46 1.23 NMT 1.2
Pseudomonic acid C7 2.03 NMT 1.2
Pseudomonic acid E8 2.24 NMT 1.2
Any other unspecified
impurity		 — NMT 1.2
Total impurities — NMT 30
1  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.
2  9-{(E)-4-[(2R,3aS,6S,7S, 8aRS)-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.
3  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.
4  (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.
5  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]but-2-enoyloxy}nonanoic acid.
6  9-((E)-4-{(2S,3R,4R,5S)-3,4-Dihydroxy-5-[(3-hydroxy-4,5-dimethyltetrahydrofuran-2-yl)methyl]tetrahydro-2H-pyran-2-yl}-3-methylbut-2-enoyloxy)nonanoic acid.
7  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.
8  11-{(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}undecanoic acid.
Assay—
0.1 M Ammonium acetate— Dissolve about 7.7 g of ammonium acetate in about 900 mL of water in a 1000-mL volumetric flask, adjust with glacial acetic acid to a pH of 5.7, and dilute with water to volume.
Solution A— Prepare a filtered and degassed mixture of 0.1 M Ammonium acetate and tetrahydrofuran (75:25).
Solution B— Prepare a filtered and degassed mixture of 0.1 M Ammonium acetate and tetrahydrofuran (70:30).
Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography 621).
pH 6.3 Phosphate buffer— Dissolve 69 g of monobasic sodium phosphate in 800 mL of water, adjust with sodium hydroxide TS to a pH of 6.3, dilute with water to 1000 mL, and mix.
Standard preparation— Dissolve an accurately weighed portion of USP Mupirocin Lithium RS in pH 6.3 Phosphate buffer. Dilute an accurately measured volume of this solution quantitatively with the same solvent to obtain a solution having a known concentration of about 0.1 mg of mupirocin per mL.
Assay preparation— Transfer an accurately weighed quantity of Cream, equivalent to about 10 mg of mupirocin, to a 100-mL volumetric flask. Add 50 mL of pH 6.3 Phosphate buffer and 25 mL of tetrahydrofuran. Insert the stopper into the flask, mix on a vortex mixer, and shake for 1 to 3 minutes. Dilute with pH 6.3 Phosphate buffer to volume. Allow to stand until the oil layer separates out, then dilute the aqueous layer with pH 6.3 Phosphate buffer to volume. Repeat 2 to 3 times until as much of the oil layer has separated out as possible. After the final dilution, pass the final solution (bottom layer) through a filter having a 0.5-µm or finer porosity. This solution will have a nominal concentration of 0.1 mg per mL of mupirocin based on label claim.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 240-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L7. The flow rate is about 1 mL per minute. Maintain the column at a constant temperature up to 35. The chromatograph is programmed as follows.
Time
(minutes)		 Solution A
(%)		 Solution B
(%)		 Elution
0 100 0 equilibration
0–6 100 0 isocratic
6–35 100®0 0®100 linear gradient
35–55 0 100 isocratic
55–55.01 0®100 100®0 immediate
55.01–65 100 0 isocratic
Chromatograph the Standard preparation, and record the peak responses as directed for Procedure. [note—Pseudomonic acid D is a minor component that is always present in mupirocin calcium. ] Identify the peaks by their retention times which are about 0.75 for pseudomonic acid D and 1.0 for mupirocin: the resolution, R, between pseudomonic acid D and mupirocin is not less than 3; the column efficiency for the mupirocin peak is not less than 7000 theoretical plates; the tailing factor for the mupirocin peak is not more than 1.75; and the relative standard deviation of the mupirocin peak for replicate injections is not more than 2%.
Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the peak area responses for the major peaks. Calculate the percent label claim of mupirocin in the portion of Cream taken by the formula:
(P / 1000)(CS / CU)(rU / rS)(100)
in which P / 1000 is the potency of mupirocin, converted from µg per mg to mg per mg, in USP Mupirocin Lithium RS; CS is the concentration, in mg per mL, of USP Mupirocin Lithium RS in the Standard preparation; CU is the nominal concentration, in mg per mL, of Cream in the Assay preparation; and rU and rS are the mupirocin peak area responses obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ahalya Wise, M.S.
Senior Scientific Liaison
1-301-816-8161		 (SM12010) Monographs - Small Molecules 1
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
61 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
1-301-816-8339		 (GCM2010) General Chapters - Microbiology
62 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
1-301-816-8339		 (GCM2010) General Chapters - Microbiology
USP35–NF30 Page 3964
Pharmacopeial Forum: Volume No. 34(2) Page 281