Colistimethate Sodium
1749.82
C57H103N16Na5O28S5 (colistin B component)
1735.80
1735.80Colistimethate sodium.
Pentasodium colistinmethanesulfonate
[8068-28-8; 21362-08-3].» Colistimethate Sodium has a potency equivalent to not less than 390 µg of colistin per mg.
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.
Constituted solution—
At the time of use, it meets the requirements for Constituted Solutions under Injections 
1
.
1.
Identification, Infrared Absorption 197K.
197K.
pH 791:
between 6.5 and 8.5, in a solution containing 10 mg per mL.
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.
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%.
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—
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 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.
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—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
| Monograph | Ahalya Wise, M.S.
Scientist 1-301-816-8161 |
(MDANT05) Monograph Development-Antibiotics |
| Reference Standards | Lili Wang, Technical Services Scientist 1-301-816-8129 RSTech@usp.org |
USP32–NF27 Page 2021