» Thiostrepton is an antibacterial substance produced by the growth of strains of Streptomyces azureus (Fam. Streptomycetaceae). It has a potency of not less than 900 USP Thiostrepton Units per mg, calculated on the dried basis.
Packaging and storage Preserve in tight containers.
Labeling Label it to indicate that it is for veterinary use only.
Identification, Infrared Absorption 197K.
Loss on drying 731 Dry about 1 g of sample in vacuum at 60 for 3 hours: it loses not more than 5.0% of its weight.
Residue on ignition 281: not more than 1.0%.
Assay Proceed as directed under AntibioticsMicrobial Assays 81, preparing the Test Dilution as follows. Transfer about 60 mg of Thiostrepton, accurately weighed, to a beaker. Add about 125 mL of dimethyl sulfoxide, and stir with a magnetic stirrer until dissolved (about 5 minutes). Transfer this solution to a 200-mL volumetric flask, washing the beaker and the stirring bar with dimethyl sulfoxide. Add the washings to the volumetric flask, dilute with dimethyl sulfoxide to volume, and mix. Dilute this solution quantitatively with dimethyl sulfoxide to obtain a Test Dilution having a concentration of thiostrepton assumed to be equal to the median dose of the Standard.
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USP32NF27 Page 3730