The international standard for oleandomycin.

At the request of the WHO Expert Committee on Biological Standardization a batch of oleandomycin was submitted to an international collaborative study in six laboratories situated in four countries. In this study the material was assayed by plate diffusion methods, which varied in details of technique and design, against the US Food and Drug Administration's reference preparation for oleandomycin. On the basis of the results obtained the material has been established as the International Standard for Oleandomycin and the International Unit of Oleandomycin is defined as the activity in 0.001176 mg of the International Standard. The US Food and Drug Administration's standard and the International Standard are each part of the same parent batch of oleandomycin and the validity of such an assay has been compared with the more usual assay situation when there is some degree of difference between the preparations under comparison.