Collaborative study for the establishment of the 2nd international standard for neomycin B.

An international collaborative study was organised to establish the World Health Organization (WHO) 2nd International Standard (IS) for neomycin B. Seven laboratories from different countries participated. Potencies of the candidate material were estimated by microbiological assays with sensitive micro-organisms. To ensure continuity between consecutive batches of the WHO IS, the 1st IS for neomycin B was used as reference. Based on the results of the study, the 2nd IS for neomycin B was adopted at the meeting of the WHO Expert Committee for Biological Standardization (ECBS) in 2012 with an assigned potency of 17640 International Units (IU) per vial. The 2nd IS for neomycin B is available from the European Directorate for the Quality of Medicines & HealthCare (EDQM).

[Standardization of the index of biological activity of the multi-component antibiotic neomycin]. / Standartizatsiia pokazatelia biologicheskoi aktivnosti mnogo-komponentnogo antibiotika neomitsina.

The characteristic features of determination of the biological activity of neomycin and its separate components A, B and C were studied. Different sensitivity of 5 test microbes to neomycins A, B and C was observed. Bac. subtilis ATCC 6633 and Bac. cereus, var. myc. 537 were the most sensitive to neomycin A. Sar. lutea were not sensitive to neomycins A and C. The diffusion capacity of neomycin A was shown to be different from that of neomycins B and C. Even minute admixtures of neomycin A in the preparations of neomycin significantly changes the dose-response curves and affected the results of the biological activity determination.