RESUMEN
An international collaborative study was organised to establish the 3rd World Health Organization (WHO) International Standard (IS) for Erythromycin. Fifteen 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, the 2nd IS for Erythromycin was used as a reference. Based on the results of the study, the 3rd IS for Erythromycin was adopted at the meeting of the WHO Expert Committee on Biological Standardization (ECBS) in 2018 with an assigned potency of 925 International Units (IU) per mg. The 3rd IS for Erythromycin is available from the European Directorate for the Quality of Medicines & HealthCare (EDQM).