U.S. PHARMACOPEIA

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Colistimethate for Injection
» Colistimethate for Injection contains an amount of Colistimethate Sodium equivalent to not less than 90.0 percent and not more than 120.0 percent of the labeled amount of colistin.
Packaging and storage— Preserve in Containers for Sterile Solids as described under Injections 1.
Constituted solution— At the time of use, it meets the requirements for Constituted Solutions under Injections 1.
Bacterial endotoxins 85— It contains not more than 2.0 USP Endotoxin Units per mg of colistin.
Sterility 71— It meets the requirements when tested as directed for Membrane Filtration under Test for Sterility of the Product to be Examined.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
Other requirements— It responds to the Identification test and meets the requirements for pH, Loss on drying, Heavy metals, and Free colistin under Colistimethate Sodium. It meets also the requirements for Uniformity of Dosage Units 905 and for Constituted Solutions and Labeling under Injections 1.
Assay—
Assay preparation 1 (where it is represented as being in a single-dose container)—Constitute Colistimethate for Injection in a volume of water, accurately measured, corresponding to the volume of diluent specified in the labeling. Withdraw all of the withdrawable contents, using a suitable hypodermic needle and syringe, and quantitatively dilute with Buffer No. 6 to obtain a solution having a convenient concentration.
Assay preparation 2 (where the label states the quantity of colistin equivalent in a given volume of constituted solution)—Constitute Colistimethate for Injection in a volume of water, accurately measured, corresponding to the volume of diluent specified in the labeling. Quantitatively dilute an accurately measured volume of the constituted solution with Buffer No. 6 to obtain a solution having a convenient concentration.
Procedure— Proceed as directed for Colistimethate Sodium under Antibiotics—Microbial 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.
Auxiliary Information— Staff Liaison : Brian D. Gilbert, Ph.D., Scientist
Expert Committee : (MDANT05) Monograph Development-Antibiotics
USP29–NF24 Page 589
Phone Number : 1-301-816-8223