Tyrothricin
» Tyrothricin is an antibacterial substance produced by the growth of Bacillus brevis Dubos (Fam. Bacteriaceae). It consists principally of gramicidin and tyrocidine, the tyrocidine usually being present as the hydrochloride. It contains not less than 900 µg and not more than 1400 µg of tyrothricin per mg.
Packaging and storage— Preserve in tight containers.
Identification— Add about 5 mg to 5 mL of p-dimethylaminobenzaldehyde TS, and shake for 2 minutes. Add 2 drops of sodium nitrite solution (1 in 150) and 5 mL of water, and mix: a blue color is produced.
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 5.0% of its weight.
Assay— Proceed as directed for gramicidin under Antibiotics—Microbial Assays 81, using a suitable, accurately weighed portion of Tyrothricin dissolved quantitatively in alcohol to yield a stock solution of convenient concentration. Dilute an accurately measured volume of this solution quantitatively and stepwise with alcohol to obtain a Test Dilution having a concentration of tyrothricin assumed to be 5.0 times the median dose level of the gramicidin Standard. Multiply the result of the gramicidin assay by 5.0 to obtain the amount of tyrothricin, in µg, in each mL of the Test Dilution.
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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 3830