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C57H103N16Na5O28S5 (colistin B component) 1735.80
Pentasodium colistinmethanesulfonate [8068-28-8; 21362-08-3].
» Colistimethate Sodium has a potency equivalent to not less than 390 µg of colistin per mg.
Packaging and storage Preserve in Containers for Sterile Solids as described under Injections 1.
Labeling Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.
USP Reference standards 11
USP Endotoxin RS
Constituted solution At the time of use, it meets the requirements for Constituted Solutions under Injections 1.
Identification, Infrared Absorption 197K.
pH 791: between 6.5 and 8.5, in a solution containing 10 mg per mL.
Loss on drying 731 Dry about 100 mg, accurately weighed, in a capillary-stoppered bottle in vacuum at a pressure not exceeding 5 mm of mercury at 60 for 3 hours: it loses not more than 7.0% of its weight.
Heavy metals, Method II 231: not more than 0.003%.
Free colistin Dissolve 80 mg in 3 mL of water, and add 0.05 mL of silicotungstic acid solution (1 in 10): no immediate precipitate is formed.
Other requirements Where the label states that Colistimethate Sodium is sterile, it meets the requirements for Sterility and Bacterial endotoxins under Colistimethate for Injection. Where the label states that Colistimethate Sodium must be subjected to further processing during the preparation of injectable dosage forms, it meets the requirements for Bacterial endotoxins under Colistimethate for Injection.
Assay preparation Dissolve a suitable quantity of Colistimethate Sodium, accurately weighed, in 2.0 mL of water, add a sufficient accurately measured volume of Buffer No. 6 to obtain a solution having a convenient concentration.
Procedure Proceed as directed for Colistimethate Sodium under AntibioticsMicrobial Assays 81, using an accurately measured volume of Assay preparation diluted quantitatively with Buffer No. 6 to yield a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard.
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USP35NF30 Page 2767