Thiostrepton
1664.89[1393-48-2].» 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
.
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.
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%.
281:
not more than 1.0%.
Assay—
Proceed as directed under Antibiotics—Microbial 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.
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.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
| Monograph | Ian DeVeau, Ph.D.
Director, Veterinary Drugs and Radiopharmaceuticals 1-301-816-8178 |
(VET05) Veterinary Drugs 05 |
| Reference Standards | Lili Wang, Technical Services Scientist 1-301-816-8129 RSTech@usp.org |
USP32–NF27 Page 3730