Polymyxin B Sulfate
Polymyxin B, sulfate.
Polymyxin B sulfate [1405-20-5].
» Polymyxin B Sulfate is the sulfate salt of a kind of polymyxin, a substance produced by the growth of Bacillus polymyxa (Prazmowski) Migula (Fam. Bacillaceae), or a mixture of two or more such salts. It has a potency of not less than 6000 Polymyxin B Units per mg, calculated on the dried basis.
Packaging and storage Preserve in tight, light-resistant containers.
Labeling Where packaged for prescription compounding, the label states the number of Polymyxin B Units in the container and per milligram, that it is not intended for manufacturing use, that it is not sterile, and that its potency cannot be assured for longer than 60 days after opening. Where it is intended for use in preparing injectable or other sterile dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable or other sterile dosage forms.
A:Liquid Chromatographic Identification Test
Mobile phase Prepare a mixture of 0.1 M tribasic sodium phosphate and acetonitrile (77:23), and adjust with phosphoric acid to a pH of 3.0. Make adjustments if necessary (see System Suitability under Chromatography 621.
Standard solution Prepare a solution of USP Polymyxin B Sulfate RS in Mobile phase having a concentration of about 3.5 mg per mL. Protect this solution from light.
Test solution Prepare a solution of Polymyxin B Sulfate in Mobile phase having a concentration of about 3.5 mg per mL. Protect this solution from light.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 212-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L1. The flow rate is about 1 mL per minute.
Procedure Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, and record the chromatograms. The chromatogram obtained from the Test solution corresponds qualitatively to that obtained from the Standard solution, exhibiting a major peak corresponding to polymyxin B1 and peaks at relative retention times of about 0.5 (polymyxin B2) and 0.6 (polymyxin B3).
B: Dissolve 2 mg in 5 mL of water, add 5 mL of 2.5 N sodium hydroxide, mix, and add 5 drops of cupric sulfate solution (1 in 100), shaking after the addition of each drop: a reddish violet color is produced.
C: A solution (1 in 20) meets the requirements of the tests for Sulfate 191.
pH 791: between 5.0 and 7.5, in a solution containing 5 mg per mL.
Loss on drying 731 Dry about 100 mg, accurately weighed, in a capillary-stoppered bottle in vacuum at 60 for 3 hours: it loses not more than 7.0% of its weight.
Content of phenylalanine Transfer about 0.375 g of Polymyxin B Sulfate, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with 0.1 N hydrochloric acid to volume, and mix. Measure the absorbances of this solution at the maxima at about 264 nm (A264), 258 nm (A258), and 252 nm (A252), and the absorbances at 280 nm (A280) and 300 nm (A300). Calculate the percentage of phenylalanine in the portion of Polymyxin B Sulfate taken by the formula:
(9.4787/W)(A258 0.5A252 + 0.5A264 1.84A280 + 0.8A300)in which W is the weight, in g, of Polymyxin B Sulfate taken: it contains between 9% and 12% of phenylalanine, calculated on the dried basis.
Other requirements If for prescription compounding, it meets the requirements for Residue on ignition under Polymyxin B for Injection. Where the label states that Polymyxin B Sulfate is sterile, it meets the requirements for Sterility Tests 71 and, where intended for injectable dosage forms, for Pyrogen under Polymyxin B for Injection. Where the label states that Polymyxin B Sulfate must be subjected to further processing during the preparation of injectable dosage forms, it meets the requirements for Pyrogen under Polymyxin B for Injection.
Assay Proceed with Polymyxin B Sulfate as directed under AntibioticsMicrobial Assays 81.
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USP32NF27 Page 3326Pharmacopeial Forum: Volume No. 28(4) Page 1183